Harry Sunarsa

VoIP(Voice over Internet Protocol)

04/11/2023 HS 2

Today we will deal with:• What is VoIP?• Ways of using VoIP?• Advantages & disadvantages?

04/11/2023 HS 3

What is VoIP?

VoIP allows you to make telephone callsusing a computer network, over a data network like the Internet

04/11/2023 HS 4

How VoIP Works

1. The voice is converted from an analog to a digital signal.

2. The digital signal is broken up into packets.

3. The packets are sent to the destination via Internet Protocol (IP).

4. The packets are reassembled into a digital signal at the destination.

5. The digital signal is converted to an analog signal and played back through the receiver.

Call Server

VoIP - Basics

AnalogVoice

AnalogVoice

Signaling Path Peer-to-peer Or client/server SIP, H.323, or H.248 …/UDP/IP or TCP/IP

Bearer Path IP-end to IP-end Encoded voice Packetized Real Time Protocol (RTP) RTP/UDP/IP

Control Path Statistics on performance of

bearer “channel” RTP Control Protocol (RTCP) RTCP/UDP/IP

ApplicationServer

VoIP Endpoint(terminal or gateway)

IP

VoIPNetwork #2

VoIPNetwork #1

VoIP Network

PSTN/ISDN

TrunkGateway

Call Server

ApplicationServer

Business

IPPBX

AccessGateway

GWHome

HomeHomeHome

AccessBorderGateway

BorderGateway

Call Server

ApplicationServer

04/11/2023 HS 7

Scenario 1: PC to PC

Need a PC with sound card IP Telephony software(softphone): Skype, Gtalk, YMessenger , … Video optional

04/11/2023 HS 8

Scenario 2: PC to Phone

Need a gateway that connects IP network to phone network

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Scenario 3: Phone to Phone

Need more gateways that connect IP network to phone networks The IP network could be dedicated intra-net or the Internet. The phone networks could be intra-company PBXs or the carrier switches

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Advantages & Disadvantages

Advantages:• Low cost - Leads to greater financial savings• Portability – Not distance or location

dependent. • Features: – 3-way calling, call forwarding, callback services

and caller ID are usually standard features (free)– managing address books, video Conference,

message or data file exchange

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Disadvantages:• No service during a power outage• Quality and Reliability – Depends on the

internet stability• Security– identity and service theft, viruses and malware,

denial of service, and spamming

Advantages & Disadvantages

04/11/2023 HS 12

Conclusion

• Overall, VoIP is a great low cost alternative for communication.

• Many companies that depend on international communication are already making use of such services in order to lower their operational costs.

• Major corporations have done some significant research to fix the disadvantages of VoIP service, as well as improve the overall quality.

• With all of the improvements continually going on with VoIP, it will soon be accepted by everyone as an acceptable alternative to PSTN.

04/11/2023 HS 13

QUESTIONS?

• Q1) Is it possible to use voip solutions in wifi enabled cellphones?

• A1) Yes , it is possible. In many cellphone operating systems there are many softphone applications which enables voip usage. For example, SJPhone is an application deployed for Windows mobile 2005 OS

• Q2) Is it possible to call the PC from the phone is used in daily life?

• A2) YES. It is possible by using DID. By the help of the special numbers which are assigned by the daily phone network to voip network, it is possible to provide the transition. This transmission is also called number of portability. (DID Number)

• Q3: What do you think about the differences in price between PSDN and VoIP?

• A3: Voip networks uses IP networks and over these networks voice packages are transferred. Internet can be used in terms of IP network. So, there is no need to additional investment. However, PSTNs performs communication over the TDM and ATM networks which have high cost. So, cost advantage between them is very high and it explains the difference in cost.

VoIP Challenges

• VoIP implementations face problems dealing with latency , echo and jitter

• Echo: waving of voice • Latency: Changing in delivery time between

voice packets• Jitter: Changing in delivery order of voice

packets

VoIP Challenges

Connection Problems:• problems behind NAT between peers.• Echo and jitter occurs because of packet loss.• Internet stability problems can cause reliability

problems and this discourages voip usage. • routing VoIP traffic through firewall may

blocks voice packets transmission.