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ZXSS10 SS1a/1b (V2.0)

Softswitch Control Equipment

Technical Manual

ZTE CORPORATION

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ZXSS10 SS1a/1b (V2.0) Softswitch Control Equipment

Technical Manual

Manual Version 20031020-R1.0

Product Version V2.0

Copyright ZTE Corporation

All rights reserved.

No part of this documentation may be excerpted, reproduced, translated, annotated or

duplicated, in any form or by any means without the prior written permission of ZTE

Corporation.

ZTE CORPORATION

ZTE Plaza, Keji Road South, Hi-Tech Industrial Park, Nanshan District, Shenzhen, P.R.China

Website: http://www.zte.com.cn

Postcode: 518057

Customer Support Center: (+86755) 26771900 800-9830-9830

Fax: (+86755) 26770801

Email: [email protected]

* * * *

S.N.: sjzl20040211

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Preface

About This Manual

This manual intends to enable users to have a systematic and complete understanding

of the ZTE Softswitch core control equipment: ZXSS10 SS1a/1b. It lays a foundation

for using other supporting manuals such as the Operation Manual, Maintenance

Manual, Command Manual and Interface Manual and conducting operation &

maintenance on the equipment.

The Technical Manual is the core of the whole set of attached manuals of the

softswitch product. All other manuals provide further descriptions on the foundation of

the Technical Manual. This technical manual primarily describes the architecture,

operating principle, software structure, performance indices, external interfaces,

service functions and application examples of the softswitch product.

Major modules:

1. Basic knowledge: describes knowledge related to the softswitch system;

2. Architecture: describes the total structure and functions of the Softswitch

product and composition of the system;

3. Technical indices: describes technical indices of the softswitch product;

4. Interfaces and protocols: describes external interfaces and communication

protocols of the softswitch system;

5. Service functions: describes the service provisioning mode and capability of the

softswitch product.

6. Networking and configuration: describes the softswitch networking mode and

application.

This Technical Manual consists of the preface, contents, text and appendix.

How to Use This Manual

This manual includes six chapters. Chapter 1 Basic Knowledge describes the basic

conceptions of the data communication network and knowledge about the packet

switching technology; Chapter 2 Architecture simply describes the composition of

the softswitch system as well as the location of the softswitch control equipment in the

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system and its functions; Chapter 3 Technical Indices describes technical indices

related to ZXSS10 SS1a/1b; Chapter 4 Interfaces and Protocols describes interfaces

and communication protocols of ZXSS10 SS1a/1b; Chapter 5 Service Functions

describe service functions of ZXSS10 SS1a/1b; and Chapter 6 Networking Mode and

Configuration describes the networking application, configuration principles and

configuration examples of ZXSS10 SS1a/1b. In addition, the appendix describes

knowledge about the common technical index analysis methods, system protocol stacks,

small-capacity core equipment ZXSS10 SS1c and abbreviations.

This technical manual is intended for deployment engineering technical personnel as

well as daily maintenance personnel and maintenance management personnel of the

equipment room. You can either select relevant chapters according to the title of each

chapter such as Architecture, Interfaces and Protocols, Service Functions and

Networking Mode and System Configuration or study the manual systematically.

The technical manual is applicable to ZTE softswitch control equipment ZXSS10 SS1a

/1b (V2.0). In actual applications, if the manual differs from the actual system version,

the contents in the actual version should apply.

Related manuals also include:

ZXSS10 SS1a/1b (V2.0) Softswitch Control Equipment Operation Manual

ZXSS10 SS1a/1b (V2.0) Softswitch Control Equipment Maintenance Manual

ZXSS10 SS1a/1b (V2.0) Softswitch Control Equipment Installation Manual-Hardware

SS1a/1b (V2.0) Softswitch Control Equipment Installation Manual-Software

ZXSS10 SS1a/1b (V2.0) Softswitch Control Equipment Hardware Manual

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Contents

1 Basic Knowledge ...................................................................................................................................... 1-1

1.1 Basic Conceptions of Data Communication ..................................................................................1-1

1.2 Network Switching Technology..................................................................................................... 1-5

1.3 Packet Switching............................................................................................................................1-7

1.4 IP Telephony Technology...............................................................................................................1-8

1.5 Common IP Voice Coding and Compression Modes .....................................................................1-9

1.6 IP Address ....................................................................................................................................1-10

2 System Overview...................................................................................................................................... 2-1

2.1 System Introduction .......................................................................................................................2-1

2.1.1 Background of Softswitch...................................................................................................2-1

2.1.2 ZXSS10 Softswitch Architecture ........................................................................................2-2

2.2 Architecture....................................................................................................................................2-4

2.2.1 Hardware Structure .............................................................................................................2-4

2.2.2 Software Structure...............................................................................................................2-4

2.3 Operating Principles of ZXSS10 SS1a/1b System......................................................................2-6

2.4 System Functions ...........................................................................................................................2-7

2.5 System Features ........................................................................................................................... 2-11

2.6 Main Functions and Applicable Scope.........................................................................................2-14

2.7 Working Conditions .....................................................................................................................2-15

3 Technical Indices.......................................................................................................................................3-1

3.1 Processing Capability.....................................................................................................................3-1

3.1.1 BHCA..................................................................................................................................3-1

3.1.2 Maximum Subscriber Capacity of System..........................................................................3-1

3.1.3 System Expansion ...............................................................................................................3-2

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3.1.4 Others.................................................................................................................................. 3-2

3.2 Charging Performance................................................................................................................... 3-2

3.3 Time Monitoring and Load Capacity............................................................................................. 3-2

3.4 Reliability and Availability ............................................................................................................ 3-3

4 Interfaces and Protocols............................................................................................................................ 4-1

4.1 Overview ....................................................................................................................................... 4-1

4.2 Physical Interface........................................................................................................................... 4-1

4.3 Protocol Interface........................................................................................................................... 4-1

5 Service Functions ..................................................................................................................................... 5-1

5.1 Overview ....................................................................................................................................... 5-1

5.2 Basic Voice Service ....................................................................................................................... 5-3

5.2.1 Basic PSTN Voice Service and Supplementary Service..................................................... 5-3

5.2.2 IP Centrex ........................................................................................................................... 5-9

5.2.3 IP Public Phone................................................................................................................. 5-14

5.3 Traditional Intelligent Service ..................................................................................................... 5-17

5.4 IP Value-added Service ................................................................................................................ 5-19

5.5 Multimedia Service...................................................................................................................... 5-20

6 Networking Mode and System Configuration.......................................................................................... 6-1

6.1 Networking Mode.......................................................................................................................... 6-1

6.1.1 Networking Mode of Backbone Network........................................................................... 6-1

6.1.2 Networking Mode of Local Network.................................................................................. 6-2

6.2 System Configuration .................................................................................................................... 6-6

AppendixA Analysis of Common Technical Indices .................................................................................. A-1

A.1 Delay Analysis ............................................................................................................................. A-1

A.2 Traffic Analysis............................................................................................................................ A-3

A.2.1 Network Traffic Analysis.................................................................................................. A-3

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A.2.2 Traffic Analysis of Softswitch Control Equipment ...........................................................A-5

AppendixB ZXSS10 SS1a/1b Protocol Stack............................................................................................. B-1

B.1 Megaco/H248 Protocol................................................................................................................. B-1

B.2 MGCP Protocol ............................................................................................................................ B-2

B.3 SCTP Protocol.............................................................................................................................. B-3

B.4 M3UA Protocol ............................................................................................................................ B-4

B.5 SIP Protocol.................................................................................................................................. B-6

B.6 No.7 UP Protocol.......................................................................................................................... B-7

AppendixC Abbreviations........................................................................................................................... C-1

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A List of Figures

Fig. 1.2-1 A Simple Communication Network .........................................................................................1-6

Fig. 1.3-1 Packet ....................................................................................................................................... 1-7

Fig. 2.1-1 Next-generation Network Based on the Softswitch Technology..............................................2-2

Fig. 2.2-1 System Architecture Connection of Softswitch Control Equipment ........................................2-4

Fig. 2.2-2 Software System of Softswitch Control Equipment................................................................. 2-5

Fig. 2.3-1 ZXSS10 SS1a/1b Platform.......................................................................................................2-6

Fig. 4.3-1 Typical Application of Protocols ..............................................................................................4-2

Fig. 5.1-1 Service Provisioning Mode of Softswitch Network .................................................................5-2

Fig. 5.2-1 Provisioning Mode of IP Centrex Service..............................................................................5-10

Fig. 5.2-2 Simplified IP Public Phone.....................................................................................................5-15

Fig. 5.2-3 Standard IP Public Phone .......................................................................................................5-16

Fig. 6.1-1 Class 4 Solution........................................................................................................................ 6-2

Fig. 6.1-2 Solution Integrating Home Data and Voice ..............................................................................6-3

Fig. 6.1-3 Pure Voice Solution of the Office (corridor).............................................................................6-4

Fig. 6.1-4 Community Solution ................................................................................................................ 6-5

Fig. 6.1-5 Intelligent Terminal Solution.................................................................................................... 6-6

Fig. B.1-1 Relationship between Transactions, Contexts and Commands............................................... B-2

Fig. B.4-1 M3UA Application.................................................................................................................. B-4

Fig. B.5-1 Typical SIP Session/Call Setup Process.................................................................................. B-6

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A list of Tables

Table 5.2-1 Supplementary Services......................................................................................................... 5-3

Table 5.2-2 Centrex Service Functions ...................................................................................................5-10

Table 5.2-3 Functions of Operator Console ............................................................................................5-13

Table 5.3-1 Traditional Intelligent Service..............................................................................................5-18

Table 5.4-1 IP Value-added Service ........................................................................................................5-19

Table 6.1-1 Various Solutions ...................................................................................................................6-2

Table 6.2-1 ZXSS10 SS1a Hardware Configuration List 1 ......................................................................6-7

Table 6.2-2 ZXSS10 SS1b Hardware Configuration List 2 ......................................................................6-8

Table 6.2-3 ZXSS10 SS1a Background Configuration List......................................................................6-8

Table 6.2-4 ZXSS10 SS1b Hardware Configuration List 1 ......................................................................6-9

Table 6.2-5 ZXSS10 SS1b Hardware Configuration List 2 ....................................................................6-10

Table 6.2-6 ZXSS10 SS1b Background Configuration List ................................................................... 6-11

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1-1

1 Basic Knowledge

Summary

This chapter describes basic knowledge related to the softswitch product, including the

basic conceptions of data communication, network switching technology, packet

switching, IP telephony technology, common IP voice codes and compression modes as

well as definition of and division principles for IP addresses. To understand the above

basic knowledge can help users to better learn the softswitch technology.

1.1 Basic Conceptions of Data Communication

Data communication is a new communication mode combining the computer and

communication, which is the foundation upon which various computer networks can be

set up. The data communication network has been developing for 30 years. In the

course when human beings enter the information society, data communication is

playing a more and more important role.

There are many conceptual terms involved in data communication. We can actually

grasp the essence of data communication only after understanding these terms.

1. Channel

The path where the transmission information is to pass is called channel. In

computers, channels are further divided into physical channels and logic

channels. The physical channel refers to the physical path used to transmit

signals or data. The physical path between two termination points in a network

is called a communication link. A physical channel is composed of transmissionmedia and relevant devices. The logic channel is also a kind of path. However,

there is no physical transmission media between the signal receiving and

transmitting points. In this case, the transmission is made possible via the edge

within the termination on the foundation of the physical channel. Generally, a

logic channel is called as connection.

2. Code element

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ZXSS10 SS1a/1b (V2.0) Softswitch Control Equipment Technical Manual

1-2

The code element is known as each bit in binary numbers transmitted over a

network, e.g.: 10101010.

3. Data

There are two types of data: analog data and digital data.

For analog data, both the time and amplitude are continuous. Its level varies

continuously with the time. For example: voices are typical analog signals.

Other signals received by analog sensors such temperature, pressure and traffic

are also analog signals. For digital data, the time is discrete while the amplitude

is quantized. It is generally a numeric sequence composed of binary codes of 0

and 1. In the communication system, signals represented with analog data are

called analog signals will those represented with numeric data are called digital

signals. They can be transformed to each other.

4. Modem

The traditional telephone communication channel is a kind of analog channel

that only transmits voice signals, which cannot directly transmit digital signals

of computers. To utilize the existing analog line for digital signal transmission, it

is required to transform digital signals to analog signals. This process is called

modulation. At the other end, the received analog signals need to be restored to

digital signals. This process is called demodulation. Since data transmission is

bi-directional generally, modulation and demodulation are needed at both ends.

The device performing such functions is called MODEM.

5. Data transmission rate

It refers to the speed of information transmission over the communication line.

The data transmission rate is represented in two ways: signal rate and

modulation rate.

Signal rate S: refers to the valid bits of binary bit codes transmitted in the unit

time. Generally, its unit is bits per second, i.e., BPS.

Modulation rate B: is the transmission rate of modulated pulse signals. Its unit is

BAUD. Generally, it is used to represent the signal transmission rate between

modulators.

The relationship between signal rate S and modulation rate B is: S=Blog2N

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Chapter 1 Basic Knowledge

Here, N indicates the valid status of a pulse signal. In the binary system, there

are two types of status for a pulse: 0 or 1, i.e., n=2. More specifically, signal rate

S is consistent with modulation rate B.

6. Bit error ratio

It refers to the error ratio of the information transmission, which is an index for

judging system reliability. It is measured on the proportion of bits in received

information on the total transmission bits. Generally, the bit error ratio should be

under 10-6

.

7. Information capacity

It refers to the highest capability of the channel in information transmission.

Generally, it is represented with the maximum number of information bits that

can be transmitted within the unit time. In actual application, the channel

capacity should be more than the transmission rate. Otherwise, it is impossible

to fully utilize the high transmission rate.

8. Baseband transmission

It refers to transmission of original 0 or 1 digital pulse signals generated by

computers or terminals over communication cables. In this way, the baseband of

a signal can be divided from a direct stream to several MHZs. The broader the

frequency band, the larger the influence of the capacitance and inductance of the

transmission line over waveform attenuation of transmission signals. Generally,

the transmission distance does not exceed 2km. If this distance is exceeded, it is

required to add relays to amplify signals, thus prolonging the transmission

distance.

9. Frequency band transmission

In long-distance communication, it is necessary to modulate digital signals to

audio signals before sending and transmitting them. The receiving end will then

demodulate received audio signals to digital signals. Therefore, when frequency

band transmission is adopted, it is required to mount modems at the transmitting

and receiving ends. This method not only solves the problem of digital signal

transmission over telephone lines but also realizes multi-channel multiplexing

and increasing the channel utilization efficiency.

10. Broadband transmission

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1-4

It refers to information transmission via media with higher bandwidth

(approximately 300-400MHz generally). During system design, this frequency

band is split into several sub-bands. With the multi-channel multiplexing

technology, multiple types of information such as sounds, images and data can

be transmitted simultaneously over one channel. In this way, the system is made

multipurpose.

11. Serial transmission

It refers to transmission of data bit by bit. In this case, only one transmission line

is needed between the transmitting and receiving ends. The advantage of this

mode is to save devices and reduce expenses. Its disadvantage is that thetransmission rate is low. The application of this transmission mode is

widespread in the current network.

12. Parallel transmission

In this case, one byte (8 bits) is transmitted each time and eight lines are used

between the transmitting and receiving ends.

At present, parallel transmission is generally used for operations within

computers. When the serial transmission is adopted, the transmitting end will

transform the parallel data stream to serial data stream via the parallel/serial

conversion device; while the receiving end will restore them to 8-bit parallel

data via the serial-parallel device.

13. Data exchange mode

Generally, computers in the network exchange data via the public

communication transmission line to increase the utilization efficiency of the

transmission equipment. The switching mode in LAN includes two categories:

line switching and storage switching. In storage switching, the packet switching

and packet group switching are commonly used.

14. Character coding

The data transmitted over the channel appear in the binary bit form. It deals with

how to combine two code elements: 0 and 1 so that they can represent different

data and information.

15. Error correction

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Errors are inevitable during the process or character code transmission and

receiving. How to detect errors in time and further correct them is also an

important topic of research for the digital communication system. The general

solutions include anti-interference coding or correction coding. At present, the

commonly solutions include adding polarity check codes, block codes, cycle

redundancy codes and so on.

16. Protocol

It refers to network communication rules, which define the mode of

communication between two computers via a network.

17. Synchronous transmission

It is a transmission mode with message and packet as the unit. Since a packet

may contain many characters, it can considerably reduce the amount of

information used in synchronization, this increasing the transmission rate. At

present, this transmission mode is adopted in most computer networks.

18. Asynchronous transmission

In this case, the unit of the data to be transmitted is character. Moreover, the

transmitting interval between characters is asynchronous, i.e., the transmitting

time of the next character is irrelevant to that of the previous character.

In the data communication system, according to the permitted transmission direction,

the following three data communication modes can be provided:

1. Simplex communication: data can be transmitted only along a fixed direction,

i.e., the transmission is unidirectional.

2. Semi-duplex communication: data can be transmitted along two directions.

However, at a moment, information can be only transmitted along one direction.

3. Duplex communication: information can be transmitted along two directions

simultaneously. This mode is commonly adopted in computer communication,

which can considerably increase the transmission rate.

1.2 Network Switching Technology

In a wide area, data communication is to transmit data from a source node to the

destination via the intermediate switching node network. Such a switching node does

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1-6

not care about contents of data. Its objective is to provide switching facilities for

mobile data between nodes. Fig. 1.2-1 shows a simple network. A termination device

for communication can be called a site. A site can be either a computer, terminal,

telephone or another communication device. A switching device providing

communication is called a node. They form a topology after being connected with each

other via transmission links. Each site can be connected with a node. The collection of

all nodes is called a communication network.

B

F

E

D

C

A

1

5

7

6

32

4

Network node

55

Termination

Fig. 1.2-1 A Simple Communication Network

In a switching communication network, the data entering the network from a site via

inter-node switching is sent to the destination after being routed. In Fig. 1.2-1, the data

sent from site A to site F are transmitted to node 4. We can set whether to send them to

the destination via node 5 and 6 or node 7 and 6. From this simple network, we can see

that:

1. Some nodes are only connected to other nodes (e.g.: node 5 and 7). The sole task

of these nodes is to complete internal data exchange. Other nodes are connected

to one or more sites. Except the exchange function, these nodes also receive data

from the connected site and delivers data to the connected site.

2. Generally, the multi-channel multiplexing is adopted for inter-node links. We

can also adopt the frequency division multiplexing (FDM) or time division

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multiplexing (TDM) mode. In addition, the network is not all connected, i.e.,

there is no direct link between each possible node pair. However, it is always

hoped that there are more than one path between each pair of sites to increase

the network reliability.

In the wide area network, two utterly different technologies are adopted: circuit

switching and packet switching. Along the path from the source to destination, there

are distinct differences between the modes of switching information from one line to

another for different nodes. Since the major softswitch bearer network is based on the

packet switching network, we will primarily describe the packet switching mode

below.

1.3 Packet Switching

In the packet switching network, data are transmitted in short packets. The upper limit

for the typical packet length is 1,000 bytes (or octet). If a longer packet is to be sent

from a source site, this packet will be split into a series of shorter packets, as shown in

Fig. 1.3-1. Each packet contains a part of user data (or the whole of a shorter packet)

and some control information. The control information should at least contain routing

information needed by the network for sending packets to the destination. At each nodeof a path, packets are received, stored for a short period of time and then transmitted to

the next node. Compared with circuit switching, packet switching has the following

advantages:

User data

Control information

Packet header

Packet

Fig. 1.3-1 Packet

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1-8

1. High line efficiency: a single inter-node link can be dynamically shared by

multiple packets. In this case, packets are queued and sent out from the relevant

link as soon as possible. However, in circuit switching, the time on the

inter-node link is allocated in advance with synchronous time division

multi-channel multiplexing. In this case, the time slot allocated to a connection

cannot be occupied by other connections even when it is idle.

2. The packet switching network can implement data rate conversion. In this case,

two sites with different data transmission rates can exchange packets with each

other since each site is connected to its communication node at the respective

rate. However, in circuit switching, the two sites connected with a circuit should

transmit and receive data at the same rate.

3. In a circuit switching network, when the traffic is high, some calls will be

blocked, i.e., the network will reject new connection requests before the load on

the network reduces. However, in a packet switching network, such packets will

still be received but the transmission delay is increased.

4. Priorities are used. If there are many packet queues to be transmitted for a node,

it can transmit packets with higher priorities in precedence. These packets will

have lower delay than those with lower priorities.

Generally, packet switching does not mean to send the whole packet of a user. Instead,

one packet is divided into several packets that can be saved in the memory. This

increases the switching speed. This mode is applicable to interactive data transmission.

According to services provided by the communication subnet for the termination

system, packet switching can be further divided into datagram and virtual circuit

switching.

1.4 IP Telephony Technology

The major objective of the IP telephony technology is to combine the IP network with

the telephony network. Moreover, IP telephones can be used by not only computer

users but also ordinary telephone users. The two networks have different characteristics:

the IP network is a kind of network transmitting data information, in which the packet

switching technology is applied; while the telephone network is a kind of network

transmitting analog voice signals, in which the circuit switching technology is applied.

As we know, the characteristic of circuit switching is that a circuit is occupied

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whenever a call is connected. It will be occupied all along as long as no party hangs up

no matter whether the two parties are talking to each other. Generally, a party is

listening while the other party is talking. Therefore, in this case, at least 50% of the

circuit is not utilized and the circuit utilization ratio is very low. The packet

transmission technology is to divide information data to be transmitted into groups

based on a certain length (i.e., cutting them to packets), add an address flag to each

packet, and then transmit them in the store-forward mode. In this case, each session

packet does not monopolize a circuit. Instead, it is sent only when the circuit is idle. In

this way, multiple sessions can share one channel asynchronously. Thus, the circuit

utilization ratio is considerably increased. Furthermore, the digital compression

technology is adopted in packet transmission. Therefore, the circuit utilization ratio is

many times higher than that of circuit switching. In addition, the charging mode of

packet transmission is irrelevant to the distance. This tremendously reduces the toll IP

cost.

At present, with the application of multiple QoS-ensuring technologies such as the

queue, priority, RSVP, VPN and MPLS, the IP network technology is developing

towards a higher rate and better QoS. Moreover, with the IP telephone technology, the

communication cost can be saved considerably. This determines its tremendous market

potential. With the driving of the market, more and more research institutes,

international standardization organizations, manufacturers etc. are devoting themselves

to the development of IP-related technologies, thus enabling it to reach the degree of

commercialization.

1.5 Common IP Voice Coding and Compression Modes

The transmission of realtime voices via the IP network is different from that of

ordinary data. In the former case, the relevant application devices must meet the

realtimeness of voices. The voice packet transmission requires the network to provide

sufficient bandwidth in time. Therefore, for most of the current IP networks that do not

provide so high rates, the voice compression technology is the key for implementing IP

voice communication. Now, we will present a brief description of the frequently used

voice coding and compression modes at present:

1. PCM

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1-10

Pulse code modulation (PCM) is the earliest digital voice technology, which

does not include any compression algorithm. It transmits voice signals with the

64kbps bandwidth, i.e., taking 8,000 samples per second and acquiring an

8-digit voice signal per sample. PCM is the standard coding mode adopted in

G.711.

2. CELP

Code excited linear prediction (CELP) is the most advanced voice transmission

technology at present. The CELP algorithm is to compare analog signal samples

with curves in the predefined code book; send codes in the code book closest to

these analog signal samples to the receiving end; and regenerate original signalsafter comparison again with the code book at the receiving end. The sampling

interval of original signals is very short. Therefore, the regenerated signals are

very close to the original signals after being filtered. CELP is the basis of

numerous advanced patented voice compression modes. Voices can be

compressed to 5.3kbps, 8kbps or 9kbps.

3. CS-ACELP

Conjugate structure algebra code excited linear prediction (CS-ACELP) or

G.729 is the 8kbps voice compression and coding standards of International

Telecommunications Union (ITU). CS-ACELP is a new algorithm, which is able

to encode 8kbps voice signal bit streams (while the rate of ordinary PCM signals

is 64kbps). The bandwidth efficiency is eight times as that of PCM and four

times as that of 32kbps ADPCM. At present, CS-ACELP is the most welcome

voice encoding/decoding plan.

When actually selecting a voice compression algorithm, it is necessary to take various

factors into consideration. For example: the pursue of higher bit rates guarantees sound

voice quality but requires to occupy more system resources. While lower bit rates will

influence voice quality and increase delay. Therefore, to keep better voice quality in the

precondition of lower bit rates is the principle for compression algorithm selection.

1.6 IP Address

For a node in the network, the Internet protocol address (IP address for short) is a logic

address. It is independent from any network hardware and network configuration. It

has the same format no matter the type of the physical network. An IP address is a

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4-byte number, which is actually composed of two parts: the first part is the IP network

No. while the second part is the host No. Generally, such a 4-byte IP address is

separated with small dots, in which each byte is indicated with a decimal number. For

example: for 130.130.71.1, the network No. is 130.130 and the host No. is 71.1.

IP addresses can be divided into five classes, i.e., Class A, Class B, Class C, Class D

and Class E. Indicates with binary codes, the highest bit of Class A addresses is 0; the

highest two bits of Class B addresses are 10; the highest three bits of Class C addresses

are 110; the highest four bits of Class D addresses are 1110; and the highest five bits of

Class E addresses are 11110. Since Class D addresses are only used in special

definition of the host group and Class E addresses are reserved for future use, only one

type in Class A, B and C addresses can be allocated for a specific network.

The IP addressing mechanism allows three types of possible network configuration. IP

addresses are the basis for inter-node communication that uses the IP protocol. This is

true for either the private TCP/IP network or public Internet.

If a user does not hope to add a network to the public Internet, the user can select IP

addresses by forced stipulation. If this method is adopted, the IP addresses for all nodes

on this network should meet the following stipulations:

1. The network No. part of each IP address is the same;

2. The IP address of each node on the network should be sole.

The highest bit 0 of a Class A address and its subsequent 7 bits belong to the network

No. part; while the remaining 24 bits indicate the intra-net host No. In this case, there

may be 126 Class A networks in an interconnected network (network No. ranging

between 1~126. 0 and 127 are reserved). While in a Class A network, there may be

16,000,000 nodes. Therefore, Class A addresses are only used in very large regional

networks, e.g., MLNET in the U.S. and some large-scale commercial networks.

The highest two bits 10 of a Class B address and the subsequent 14 bits belong to the

network No. part; while the remaining 16 bits indicate the intra-net host No. In this

case, there may be about 16,000 Class B networks. While in a Class B network, there

may be more than 65,000 nodes. Class B addresses are generally used in networks

constructed by large institutions and companies.

The highest three bits 110 of a Class C address and the subsequent 21 bits belong to the

network No. part; while the remaining 8 bits indicate the intra-net host no. In this case,

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an interconnected network is allowed to include 2,000,000 Class C networks. In each

Class network, there can be a maximum of 254 nodes. Class C addresses are used in

small-scale institutions and companies.

If you do not like to use the binary system, you can also divide the three types of

networks according to the decimal numbers of the first bytes of IP addresses. Class A

address range between 1~126; Class B addresses range between 128~191; and Class C

addresses range between 192~223.

As in the convention, when the binary codes of the entire network No. part (the first

byte for Class A; the first two bytes of Class B; and the first third bytes for Class C) are

all zeros, the network No. is considered as the local network; when the binary codes ofthe host No. part (the last three bytes for Class A; the last two bytes for Class B; and

the last byte of Class C) are all ones, the host No. is considered as the broadcast

address within the local network.

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2 System Overview

Summary

The chapter introduces the overall structure, operating principles, major functions,

characteristics, major purposes and applicable range of the ZXSS10 SS1a/1b softswitch

control equipment system.

2.1 System Introduction

2.1.1 Background of Softswitch

At present, two totally independent networks exist: the PSTN network and data

network, which provide the voice service and basic data service respectively.

Network separation and isolation of operation & maintenance have been keeping the

general network operation & maintenance costs on a high level, and furthermore, a

network cannot provide complicated convergence services, although the network

convergence has been an inevitable trend.

Since a traditional voice network is a closed network with monopolized resources, it

has become a common understanding in the telecom industry that the packet network

(typically, the Internet), with the advantages such as open architecture, low costs and

large scale, will replace the PSTN to become the basic frame of the next generation of

convergence networks and that the construction of the next generation of networks will

be based on current packet networks.

It is necessary for carriers to consider resource utilization and investment protection

during construction of future networks. On one hand, carriers should trace the latest

technologies; and on the other hand, they should try to utilize existing technologies and

resources. Thus, carriers can provide users with large numbers of services

economically and rapidly to make the highest profits, without the need of large-scale

network alteration.

The solution of smooth transition from existing networks to the next generation

networks is the key to the problem. The Softswitch solution based on softswitch

technology is just a mainstream solution to smooth network evolution.

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2.1.2 ZXSS10 Softswitch Architecture

Hierarchical models are adopted for the Softswitch-based next generation network. The

entire network can be divided into four layers: Service Layer, Control Layer, Core

(Transport) Layer and Edge Access Layer, as shown in Fig. 2.1-1.

Service layer

Control layer

Core layer

Edge layerTGSG

IP

PBXAG NAS MSAG WAG

No.7 Network

IAD

Broadband AccessWireless

IP Router/ATM Swtich

Core Packet Network

ZXSS10 SS

Softswitch

SCP DatabaseAAA Server Application Server Policy Server

ZXSS10 SS

Softswitch

PSTN / ISDN

H.323

GW

SG: signalling gateway TG: trunk gateway AG: access gateway

NAS: narrow-band access server IAD: integrated access device WAG: wireless access gateway

H.323GW: H.323 gateway IP PBX: IP-based private branch exchange MSAG: multi-service access gateway

Fig. 2.1-1 Next-generation Network Based on the Softswitch Technology

1. The edge access layer refers to various access gateways and new types of access

terminal devices related to the current network. It implements interworking with

the existing various types of communication networks and provides access of

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Chapter 2 System Overview

various communication terminals (e.g., the analog phone, SIP Phone, PC Phone

visual terminal and intelligent terminal) to the IP core layer.

2. The Core (Transport) Layer refers to a packet switching network composed of

backbone transmission equipment such as IP router or broadband ATM switch,

which is the bearer basis of a softswitch network.

3. The Control Layer refers to Softswitch control units, which completes integrated

control processing functions such as call processing control, access protocol

adaptation, interconnection and interworking and provides an application

support platform for the entire network.

4. The Application Layer provides a network with various applications and

services, client-oriented integrated intelligent services and service

customization.

Where, standard interfaces are used for communication between layers. Under the

control of the core equipment (i.e., the Softswitch control equipment) and based on

division of labor and cooperation of work, the related NE equipment implements

various service functions of the system.

In softswitch architecture, the softswitch control equipment is the core, which is

independent of the bottom-layer bearer protocols and implements functions such as call

control media gateway access control, resource allocation, protocol processing, routing,

authentication and accounting. The softswitch control equipment can provide all basic

call services, supplementary services and point-to-point multimedia services a PSTN

can provide. Furthermore, with the cooperation of the Service Layer equipment (SCP)

and Application Server, the equipment also can provide users with traditional

intelligent services, value-added IP services, diverse third-party value added services

and new intelligent services.

ZXSS10 SS1a is a piece of softswitch control equipment with medium capacity, which

can process hundreds of thousands of calls. ZXSS10 SS1b is a piece of softswitch

control equipment with large capacity, which can process millions of calls.

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2.2 Architecture

2.2.1 Hardware Structure

Compared with a traditional switch, the hardware structure of the softswitch control

equipment is relatively simple, which mainly includes the foreground realtime

processing part, the background (OSS and Database Server) and System Switching

Network (SSN) card interconnection all internal modules. The connection is shown

in Fig. 2.2-1.

Database

Server

IP

ZXSS10 SS1a/1b

Real-time

processing part

Operation & maintenance terminal

Fig. 2.2-1 System Architecture Connection of Softswitch Control Equipment

ZXSS10 SS1a/1b uses a dedicated hardware platform based on multi-processor cards.

Compared to PC platforms or commercial workstation platforms, ZXSS10 SS1a/1b is

characterized by advantages of large capacity, high density, high reliability and high

cost-performance ratio.

2.2.2 Software Structure

Designed in the distributed mode, the software system of ZXSS10 SS1a/1b has the

hierarchical and modular features. The software system is independent of the specific

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hardware platform, so the upgrading is very convenient. The schematic diagram is

shown in Fig. 2.2-2.

Softswitch ZTE

Resource

Manager

DataBase

Softswitch

Appl. Server

Call

Server

BICC/

SIP-T

Service

Manager

Data

Manager

New

Device

Adapter

H.323

Device

Adapter

SIP

Device

Adapter

H.248

Device

Adapter

No.7

Device

Adapter

SG

SIP

PhoneMG

Access

Server

H.323

GW

New

Device

SG: signalling gateway MG: media gateway H.323GW: H.323 gateway

Fig. 2.2-2 Software System of Softswitch Control Equipment

Where, the Device (Protocol) Adaptation Layer is responsible for accessing various

external standard protocols such as H.248, MGCP, H.323 and No.7, converting them to

unified internal messages and sending them to the Call Server for proper processing.

For future protocols, we can implement the upgrading of the system smoothly just by

adding the corresponding software adaptation module to this layer.

As the control core of the system, the Call Server provides unified call control. The

Resource Manager is responsible for allocating various call-related media resources,

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for example, controlling the media server to play service tones. The BICC/SIP-T

module supports interworking between peer entities (softswitch control equipment).

The Service Manager is responsible for providing interaction between the softswitch

control equipment and the upper-level SCP and Application Server. The Data Manager

provides a unified access interface to the internal database.

2.3 Operating Principles of ZXSS10 SS1a/1b System

The ZXSS10 SS1a/1b softswitch control equipment uses a dedicated hardware

platform based on the multi-processor card structure and taking high-speed serial data

bus as the core and the Ethernet structure as the foundation. It takes a set of switch

Ethernet bus as the communication and data bus within the system, as shown in Fig.

2.3-1.

Network interface

Network interface

Core switching

network

Protocolprocessor card

Protocol

processor card

System main

control

IP network

Protocol

processor card

Fig. 2.3-1 ZXSS10 SS1a/1b Platform

As the system core, a processor module mainly implements core functions such as

network control and service generation. Processor modules are connected via a fast

Ethernet to form a parallel multi-processor system in the "loose coupling" mode. The

main control processor card at the system slot controls each processor card and

allocates different tasks. Multiple processor cards implement mutual communication

and message data forwarding via the Ethernet.

The network interface module provides external interfaces with various gateway

devices via an IP network and internal interfaces with various application servers,

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database, AAA server, management maintenance terminal and intelligent network SCP.

In consideration of security, the two types of interfaces are physically independent. For

the convenience of networking, the external interfaces can provide the routing function

and configure some static routes so as to guarantee flexible and convenient access to

the IP core network.

2.4 System Functions

ZXSS10 SS1a/1b softswitch control equipment mainly completes the following

functions:

1. Call processing control

The equipment is responsible for completing the basic and enhanced call

processing.

The equipment controls setup, hold call release of basic calls, including call

processing, connection control, intelligent call triggering detection and resource

control. It supports the receiving of monitoring requests from the service

switching function and the processing of the call-related events. ZXSS10

SS1a/1b softswitch control equipment receives the information related to call

control from the service switching function and supports call setup and

monitoring.

ZXSS10 SS1a/1b softswitch control equipment supports basic two-party call

control and multi-party call control. The support of multi-party control functions

includes the control of special logical relationship between multi-party calls,

join/exit/isolation/audit of call members and mixing process. The equipment

also identifies events such as hook-off, dialing and hook-on reported by the

media gateway, controls the media gateway to send various signaling tones

(such as dialing tone, ringing tone, ring-back tone, etc.) to subscribers and

provides dial-up plan meeting the carriers requirements.

ZXSS10 SS1a/1b softswitch control equipment can cooperate with a signalling

gateway to complete the setup and release of a complete call. It uses the No.7/IP

protocol and mainly uses the bearer protocol of SCTP. Furthermore, the

equipment can control the media gateway to send IVR so as to implement

various services such as secondary dialing.

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ZXSS10 SS1a/1b softswitch control equipment can be directly connected to

H.248 terminals, MGCP terminals and SIP Client to provide the corresponding

services.

If a ZXSS10 SS1a/1b softswitch control equipment is located on a local

PSTN/ISDN network, it has the call processing function of local telephone

switching equipment. If the softswitch control equipment is located on a

PSTN/ISDN toll network, it has the call processing function of toll telephone

switching equipment.

2. Adaptation of access protocols

ZXSS10 SS1a/1b softswitch control equipment is responsible for adaptation

processing of various access protocols (signaling).

The ZXSS10 SS1a/1b softswitch control equipment is an open and

multi-protocol entity, which communicates with various media gateways,

terminals and networks via standard protocols. These protocols include: H.248,

SCTP, ISUP/IP, TUP/IP, INAP/IP, H.323, RADIUS, SNMP, SIP, M3UA, MGCP

and SIP-T.

3. Service provisioning/interfacing

ZXSS10 SS1a/1b softswitch control equipment can provide services a

PSTN/ISDN switch can provide, including basic services and supplementary

services. The equipment can cooperate with the SCP on an existing intelligent

network to provide services the existing intelligent network can provide; and

also it can cooperate with the Application Server to provide various value-added

services.

ZXSS10 SS1a/1b provides standard INAP interface with an intelligent network

and provides interfaces with an interface with the Application Server for the

convenience of service development of the third-party service provider.

4. Interconnection and interworking

As an external interface of the softswitch system, ZXSS10 SS1a/1b softswitch

control equipment is responsible for completing the interconnection and

interworking with other peers.

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ZXSS10 SS1a/1b softswitch control equipment supports the application of a

signalling gateway to implement the interworking between an existing packet

network and an existing SS7 network.

ZXSS10 SS1a/1b softswitch control equipment implements interworking with

an existing intelligent network via a media gateway and can provide users with

various intelligent services. The Media Server and media gateway under the

control of ZXSS10 SS1a/1b softswitch control equipment implement functions

such as IVR necessary for intelligent services.

By means of an interworking module and the H.323 protocol, ZXSS10 SS1a/1b

softswitch control equipment implements interworking with an IP telephonenetwork with the H.323 architecture.

ZXSS10 SS1a/1b softswitch control equipment implements interworking with

future SIP network architecture by means of the SIP protocol.

ZXSS10 SS1a/1b softswitch control equipment implements interworking and

interconnection with softswitch control equipment by means of the SIP-T

protocol.

ZXSS10 SS1a/1b softswitch control equipment supports the interworking

between H.248 terminals, SIP terminals and MGCP terminals in an IP network.

5. Application support

ZXSS10 SS1a/1b supports applications such as accounting, authentication,

operation and maintenance, etc.

ZXSS10 SS1a/1b softswitch control equipment does not provide a billing

system itself, which is only responsible for generating Call Detail Records

(CDRs). If a call ends, the equipment can output the corresponding charging

data immediately. For a call with long duration, the charging data can also be

output during the call.

By means of standard protocols, ZXSS10 SS1a/1b softswitch control equipment

can be connected to the Billing Center to transfer the charging data, i.e., CDRs.

Where, for ordinary services, the Billing Center can use the FTP protocol to

collect the charging data provided by the softswitch equipment periodically (the

minimum periodic data connection period is 5 minutes). For accounting card or

prepaid service, the softswitch control equipment uses the Radius protocol to

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transfer the charging data to the Billing center in real time, with the realtime

disconnection function.

ZXSS10SS1a/1b softswitch control equipment and the accounting system can

transfer subscriber information such as account opening and cancellation via a

standard XML interface.

ZXSS10 SS1a/1b softswitch control equipment supports access authentication of

users and gateway equipment so as to prevent access of unauthorized users and

equipment.

ZXSS10 SS1a/1b softswitch control equipment provides perfect operation &

maintenance and supports local maintenance management. Furthermore,

ZXSS10 SS1a/1b softswitch control equipment supports SNMP-based network

management mechanism and centralized remote network management, which

can be included into the unified management of the network management center

with other NE equipment in the system.

6. Address resolution

ZXSS10 SS1a/1b softswitch control equipment is responsible for the translation

from E.164 addresses into IP addresses and supports the address resolution

function.

7. Voice processing

ZXSS10 SS1a/1b softswitch control equipment can control whether a media

gateway should use voice compression and can provide the optional voice

compression algorithms, such as G.711, G.723 and G.729.

ZXSS10 SS1a/1b softswitch control equipment can control whether a media

gateway should use the echo cancellation technology.

ZXSS10 SS1a/1b softswitch control equipment also can provide the media

gateway with the size of the voice packet buffer so as to reduce the influence of

jitter on voice quality.

8. Resource control

ZXSS10 SS1a/1b softswitch control equipment provides resource management

so as to perform centralized management over various system resources, such as

allocation, release and control of resources.

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2.5 System Features

In the respect of design, the ZXSS10 SS1a/1b softswitch control equipment uses the

most advanced design method: distributed system design, which not only effectively

reduces the risk in running of the entire system but also increases the processing

capability and efficiency of the system. A dedicated communication equipment

platform serves as the hardware platform of the system and a realtime multi-task

operating system serves as the software platform, which completely guarantees the

requirements of carrier-class operation equipment for large capacity and high reliability.

Therefore, the products have very high cost-performance ratio.

As the core equipment of the next generation of networks, ZXSS10 SS1a/1b softswitchcontrol equipment is characterized by the following performances:

1. Powerful networking capability

1) With different combinations of ZXSS10 SS1a/1b softswitch control equipment

and gateway equipment, for example, SS + TG + SG, SS + AG and SS + IAD,

different toll networks and local networks can be organized to provide toll

solutions, local solution and integrated toll and local solutions.

2) The system depends upon widely distributed data networks as bearer networks

and supports various network topologies such as start, tree, ring, start + ring, etc.

3) The system has powerful penetration capability and supports various network

scales. Therefore, the system not only can provide services for a large number of

centralized users, but also can expand all services to scattered users on edges of

tones.

4) The system inherits the advantages from existing networks perfectly and

supports the complete interworking with PSTN/ISDN networks, No.7 signaling

networks and mobile communication networks.

5) ZXSS10 SS1a/1b softswitch control equipment provides perfect integrated

Network Management System (NMS) and standard network interfaces so that it

can be connected to the local network management center flexibly and

conveniently. ZXSS10 SS1a/1b provides detailed CDRs and sends the CDRs to

the Billing Center via a standard interface so as to implement centralized

settlement in the Billing Center.

2. Perfect integrated equipment access capability

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1) ZXSS10 SS1a/1b softswitch control equipment supports direct access of various

types of gateway equipment, including trunk gateway, access gateway,

signalling gateway, media gateway, wireless access gateway, integrated access

device, etc.

2) The system supports the direct access of media server.

3) The system supports the direct access of various digital terminal devices such as

PC, Softphone and IP Phone.

4) The system supports policy-based device control, dynamic addition new devices

and dynamic domain adjustment.

5) The system supports the direct access of existing H.323 network devices such as

H.323 gateways and H.323 terminals.

3. Powerful network interworking capability

1) By means of gateway equipment, the system supports the complete interworking

with various existing networks such as PSTN/ISDN networks, No.7 signaling

networks, INs and PLMNs.

2) With the application of standard protocols, the system supports the interworking

between the same or heterogeneous networks among different manufacturers

and carriers.

4. Perfect scalability

1) The system is of a layered (hierarchical) architecture. The layers are mutually

independent and can develop independently.

2) The distributed mode is used in system design so that the system can implement

smooth capacity expansion conveniently.

3) With the plane structure, the system supports the networking mode with

multi-domain expansion so that the user can plan the network construction scale

according to the specific requirements.

5. Powerful service capability

1) With the hierarchical (layered) architecture, the services provided by the system

are independent of the network and media. Once a service is generated, it can be

shared by the entire network.

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2) As a unified service proxy and service bearer platform, the softswitch control

equipment masks the complexity of the bottom-layer network for the Service

Layer, for the convenience of the generation of complicated integrated services.

3) There are three service provisioning modes: The softswitch control equipment

provides services itself; the equipment cooperates with the traditional SCP to

provide services; and the equipment cooperates with the Application Server to

provide services. Such service provisioning modes completely guarantee that the

system has perfect flexibility in utilizing existing resources and developing

future services and that the user can select and expand services flexibly and

conveniently according to the specific requirements.

6. Perfect manageability and operability

1) The equipment provides an integrated NMS, supports three interface modes

(GUI, CLI and WEB) and can implement network management functions such

as centralized maintenance, network management, fault management and static

configuration management.

2) The system provides complete operation & maintenance functions for itself,

including Element Management System (EMS) functions such as CLI, authority

management, log, traffic statistics, signaling tracing, SNMP, data configuration,

alarm and diagnosis test. The system has the features of good openness, perfect

performance, high security and rich functions, and furthermore, it can provide

detailed CDRs to that the Billing Center can perform centralized charging. The

system uses a large network database as its data platform and provides multiple

charging data backup modes, so as to guarantee the security of charging data and

fully meet the actual requirements of telecom operation.

7. High reliability

1) With respect to hardware design, the equipment provides hot backup for all

important components and all cards support hot swap with full fault tolerance

consideration, so as to guarantee that no single-point fault will occur during the

running.

2) The redundant active/standby mode or distributed cluster mode (even the remote

fault tolerance mode) is used in equipment networking. The components in each

key system are also redundant and host swappable.

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3) As for software, the equipment provides hot backup for all important data. If the

active system fails, the standby system will take over all calls under

conversation and ringing, complete the calls and save the call records.

4) The system the requirement for 99.99% reliability of carrier-class equipment.

8. Security

1) Network security

The system supports setting of different levels of administrator authority, thus

preventing users from conducting excessive operations on the equipment. For

users attempting to enter the system illegally, the background maintenance

terminal provides realtime LOG information records. For requests that have

hidden threats to the equipment, such as repeated authentication failures,

dangerous IP address connections and concurrent large traffic, graphic alarm

prompts will be given. In addition, ZXSS10 SS1a/1b provides some built-in

self-test security tools, thus automatically rejecting doubtful invasions and

reporting them to the system.

2) User security

The ZTE softswitch system provides an equipment authentication code for each

valid device whose access is permitted. It judges whether to access a subscriber

via an authentication code.

2.6 Main Functions and Applicable Scope

A network based on softswitch technology has the basic features of a Next Generation

Network (NGN), which can provide integrated multimedia services such as data, voice

and video in a centralized manner. The current versions of softswitch systems provide

voice-related services and IP value-added services, including:

1. Local service on Metropolitan Area Network (MAN)

2. Network and service interworking with existing PSTN and IN.

3. Toll service on backbone data networks

4. WEB-based IP value-added service.

Furthermore, these systems also can provide point-to-point multimedia communication

services.

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In the above various applications, ZXSS10 SS1a/1b softswitch control equipment, as

the control core of the system, is responsible for processing basic functions such as call

control, protocol adaptation and resource management. And furthermore, as the

charging collection point of the system, the equipment provides CDRs of all calls

serving as the basis of the Billing System.

2.7 Working Conditions

Packet switching (packets) networks are the bearer basis of Softswitch networks, which

are responsible for forwarding and routing of all information. Same as routers and

ATM switches, ZXSS10 SS1a/1b softswitch control equipment and other relateddevices such as media gateway, signalling gateway, Application Server, media Server

are nodes on packet networks and are connected via widely distributed packet

networks.

ZTE softswitch system ZXSS10 provides IP-based solutions. All packet networks

bearing IP services and the related technologies can serve as the bearer basis of

Softswitch networks, such as IP over ATM, IP over FR, IP over SDH and IP over

DWDM.

To construct an integrated service network based on ZXSS10 series equipment, first

build perfect packet networks supporting IP services. In actual construction, the

construction of a packet switching network can be synchronized with that of a

Softswitch integrated service network.

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3-1

3 Technical Indices

Summary

This chapter introduces such technical indices as the processing capability, charging

performance, time monitoring, loading capability, reliability and availability.

3.1 Processing Capability

3.1.1 BHCA

A single frame of ZXSS10 SS1a softswitch control equipment with medium capacity

supports 500K BHCAs.

A single frame of ZXSS10 SS1a softswitch control equipment with large capacity

supports 2000K BHCAs, and the cascading of three frames can support a maximum of

6000K BHCAs.

3.1.2 Maximum Subscriber Capacity of System

If the processing capability is given, the maximum number of digital trunks depends

upon the specific traffic model.

When the average traffic on busy per trunk is 0.7Erl and the average traffic on busy per

subscriber is 0.1Erl:

ZXSS10 SS1b is a kind of large-capacity softswitch control equipment. According to

the above traffic model, it can be estimated that the system provides the processing

capability of a maximum of 200,000 trunks or 2,000,000 subscribers.

ZXSS10 SS1a is a kind of softswitch control equipment with media capacity launched

for medium/small-capacity networks or enterprise/industry users in the current market.

Under the same traffic model, the equipment provides the processing capability of

30,000 trunks or 300,000 subscribers, thus sufficiently meeting the network

construction demands of telecom carriers.

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3.1.3 System Expansion

ZXSS10 SS1a is a kind of medium capacity softswitch control equipment and ZXSS10

SS1b is a kind of large capacity softswitch control equipment. If SS1a cannot meet the

capacity requirements, it is recommended that ZXSS10 SS1b be used directly. By

configuration of different numbers of cards (SPCs), SS1b can provide a processing

capacity ranging from hundreds of thousands of subscribers to several million

subscribers. In full configuration, SS1b can process two million subscribers. If

necessary, frame expansion can be used to further improve its processing capability.

ZXSS10 SS1b supports cascading of three frames.

3.1.4 Others

The equipment supports 60 parties to attend the same conference at maximum.

3.2 Charging Performance

The major charging performance indices are as follows:

1. Charging error ratio:

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Chapter 3 Technical Indices

6. Howler tone time supervision: 40 seconds

7. The time for listening the busy tone is 40s (adjustable).

3.4 Reliability and Availability

ZXSS10 SS1a/1b softswitch control equipment is a carrier-class product. All major

hardware boards support active/standby hot backup and power-on hot

plugging/unplugging. It meets the 99.999% reliability requirements of carrier-class

equipment and the maximum fault time per year is less than 5.3 minutes.

The complete boot time of ZXSS10 SS1a/1b softswitch control equipment includes

version load time and data load time. Where, the data load time is closely related to the

specific data volume (please do not treat all data load times as the same). Normally, the

version load time is less than two minutes.

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4-1

4 Interfaces and Protocols

Summary

This chapter introduces the connection of the product with the entire network, the

provided internal/external interfaces and used signalling/protocols. It enables users to

have a full understanding of the connection modes of the equipment and other

products.

4.1 Overview

The ZXSS10 SS1a/1b softswitch control equipment is the control core in the softswitch

system, which also serves as the external interface of the entire system. SS1a supports

multiple signaling protocols, which can provide interactions with other networks such

as PSTN, H.323 and SIP.

In addition, as an NE in the packet network, the SS1a/1b softswitch control equipment

also provides the Ethernet interface for connection with the data network.

4.2 Physical Interface

The 100Base-T Ethernet (RJ 45) interface serves as the interface between the ZXSS10

SS1a/1b softswitch control equipment and data network.

It complies with the Ethernet standards of IEEE802.3 and IEEE 802.3u.

4.3 Protocol Interface

The ZXSS10 SS1a/1b softswitch control equipment is a multi-protocol entity, which

interacts and coordinates with other NEs in the softswitch network via various standard

protocols (interfaces) to perform functions needed in the system together.

The ZXSS10 SS1a/1b softswitch control equipment supports the following protocols:

1. Call processing protocol

ISUP, TUP over IP, SIP-T and H.323

2. Transmission control protocol

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TCP, UDP, SCTP and TCAP/SCCP/M3UA

3. Media control protocol

H.248, SIP and MGCP

4. Service application protocol

INAP (CS2), LDAP and RADIUS

5. Maintenance management protocol

SNMP

The typical application of various protocols is shown is shown in Fig. 4.3-1.

SCP

App Server

Softswitch Softswitch

IP Core Network

AAA Server

SG MG MG

IAD

INAP/TCAP

ISUP/MTP

ISUP/IP

INAP/TCAP/IP

SIP-T

TDM

TDM

H.248

API/SIP

H.248/MGCP

H.323GW

SIP

H.323

NMS

SNMP

SNMP

SNMP

ComputerSIP Phone

No.7 Network

PSTN/ISDN

Control and signalling stream

SNMP

Radius

Media and control stream

ComputerTelephone

Telephone

TelephoneComputer

1 2 3

4 5 6

7 8 9

* 8 #

SG: signaling gateway MG: media gateway IAD: integrated access device

H.323GW: H.323 gateway AAA: AAA server

Fig. 4.3-1 Typical Application of Protocols

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5 Service Functions

Summary

This chapter introduces various functions implemented by the product. It presents a

detailed description of various functions and their implementation so that users can

understand service functions provided by the system.

5.1 Overview

The ZXSS10 SS1a/1b softswitch control equipment has powerful service capability.

The system is designed with the hierarchical network framework (as shown in Fig.

5.1-1). The service provisioning is independent from the network and media. Once the

service is generated, it will be shared by the entire network. The flexible service logic

creation environment enables carriers to avoid dear hardware upgrade costs and

relevant technology and transportation costs when launching new services. Services

can be provided flexibly by developers, carriers or soft corporations authorized by

carriers and the third party. Compared with the traditional method, carriers are able to

launch new services more quickly without lower costs.

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SCP

Parlay GW

Softswitch Softswitch

IP Core Network

App Server

SG MG MG

Telephone

IAD

Computer

Telephone

INAP/TCAP

ISUP/MTP

ISUP/IP

INAP/TCAP/IP

API/SIP

SIP-T

TDM

TDM

H.248

Third Party Server

H.248/MGCP

Computer

Telephone

ComputerNo.7 Network

PSTN/ISDN

Telephone Signalling st ream

Media stream

H.248H.248

App Server

Parlay/Corba

Parlay/Corba

SG: signalling gateway MG: media gateway Parlay GW: Parlay gateway IAD: integrated access device

Fig. 5.1-1 Service Provisioning Mode of Softswitch Network

The ZXSS10 SS1a/1b softswitch control equipment supports three service provisioning

modes:

1. The ZXSS10 SS1a/1b softswitch control equipment directly provides the basic

PSTN service, supplementary service and point-to-point service video service;

2. The equipment acts as the virtual SSP via interworking with existing SCP to

provide the traditional intelligent service.

The softswitch control equipment provides two modes for interworking with

SCP:

1) Interworking with SCP via SG in the standard No.7 mode;

2) Direct interworking with SCP via the extended INAP protocol on the basis of the

TCP/IP connection.

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Chapter 5 Service Functions

3. The equipment provides the IP value-added service, intelligent service and

future multimedia service by means of supporting the application server.

The WEB Server is added into the network, which acts as the service registration and

selection platform for IP subscribers and the service subscriber window. In the specific

application, the standard service API interface of the application server can be provided

for a third party developer, who can incessantly develop various new services for

subscribers. The application server can also be leased to enterprise group users, who

can provide customized services for subscribers. Moreover, the application server can

be provided for network carriers as the value-added service platform.

5.2 Basic Voice Service

The basic voice service refers to the service of which the major purpose is to ensure

normal conversation between subscribers. It is a service collection instead of a specific

service. It includes the basic call service, basic PSTN voice service and such voice

services as the supplementary service and traditional intelligent service.

Here, the basic call service refers to the local, domestic and international automatic

incoming call and outgoing call services of various terminals. The terminal type

includes the ordinary phone accessed via IAD, Soft Phone and various IP Phones based

on H.248, MGCP, SIP and H.323. The basic call service is provided by the softswitch

control equipment independently.

5.2.1 Basic PSTN Voice Service and Supplementary Service

The ZXSS10 SS1a/1b softswitch control equipment can provide all basic PSTN voice

services and supplementary services specified in YDN 065-1997 Overall Technical

Specifications for Telephone Switching Equipment of MPT and its supplementary

specifications. The supplementary services are shown in Table 5.2-1.

Table 5.2-1 Supplementary Services

Service Name Service Description

Call forwarding

Automatically forward calls to this phone to the temporarily specified

phone set. According to actual needs of subscribers, four services can

be provided: call forwarding on busy, call forwarding on no reply,

call forwarding unconditional (forwarding of all calls) and call

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forwarding on subscriber offline.

Toll prohibited in call

forwarding

After registering call forwarding, a subscriber can use this service so

that calls are not forwarded to toll numbers. This service needs to be

used together with call forwarding.

Forwarding of incoming

toll prohibited

After registering call forwarding, a subscriber can use this service so

that incoming calls other than tolls are forwarded while incoming

tolls are intercepted. This service needs to be used together with call

forwarding.

Call registering on busy

When a subscriber calls another subscriber but the called party is

busy, the call can be recorded. Within 20 minutes, if the subscriber

wants to call that subscriber again, the subscriber just needs to pick

up the phone and wait for 5 seconds without dialing any number to

call that subscriber automatically.

Callback on busy

When the called party is busy, the caller can hang up and wait

without dialing any number. Once the phone of the called party is

idle, automatic callback will be available.

CW

It is permitted that a subscriber in conversation is notified of an

incoming call. The subscriber can select to accept or ignore this

waiting call. After accepting it, the subscriber can switch

conversation between these two callers. In this case, one caller will be

held (hearing the waiting music). In addition, the subscriber can also

interrupt the conversation with a caller and only converse with the

other caller.

Absent subscriber service

When there is an incoming call but the subscriber is out, the office

can provide a voice service to reply the call for the subscriber so as to

avoid repeated dialing of the caller.

Do not disturb

When the subscriber does not hope to reply any call, the office can

reply all incoming calls for the subscriber. Moreover, outgoing calls

of the subscriber will not be affected.

"Do not disturb" in

limited time

With this service, the subscriber can be exempt from interference of

outside calls within 12 hours (adjustable for the equipment buyer).

Moreover, outgoing calls of the subscriber will not be restricted.

Malicious call tracing

When being annoyed by an unknown malicious call, a subscriber can

query the number of the malicious call from the office simply by key

pressing.

Instant malicious call

It is a supplementary for the service of look for malicious calls. With

this service, all incoming calls will be recorded in alarms of the

equipment buyer.

Multi-subscriber number The analog subscriber is provided with the MSN function. In

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Chapter 5 Service Functions


addition, there are different rings for different numbers.

Transfer service

When a subscriber is in conversatio

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