Metaswitch - Sip Market Overview

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An analysis of SIP technology andthe state of the SIP market

Text of Metaswitch - Sip Market Overview

  • 100 Church Street, Enfield, Middlesex, EN2 6BQ | www.metaswitch.com

    SIP Market Overview

    An analysis of SIP technology and the state of the SIP market

    Jonathan Cumming, jonathan.cumming@metaswitch.com

    First issued September 2003

  • 100 Church Street, Enfield, Middlesex, EN2 6BQ | www.metaswitch.com

    Executive Summary

    Session Initiation Protocol (SIP) is continuing to develop rapidly and it is difficult

    to keep up with all of its innovations and uses. This white paper is aimed at

    people who want to understand the concepts and drivers behind SIP adoption,

    and how it is evolving to face new challenges.

    This paper summarizes where SIP has come from, how it works, and what makes

    it such a useful protocol. It then describes how SIP is used in applications

    including telephony, conferencing and messaging, and how it is being extended

    to provide innovative services and accommodate the requirements of real-world

    deployment, where NATs, service level agreements and regulators exist.

    In covering this broad range of SIP-related topics, it provides a summary of the

    state of this increasingly important protocol.

    About the Author

    Jonathan Cumming is Director of Marketing, Protocol Software at Metaswitch.

    Previously, he was development manager for DC-SIP, Metaswitchs SIP User

    Agent and Proxy Server Toolkit, and retains product management responsibility

    for the product.

    Jonathan has over 15 years' experience in the communications software industry.

    He holds an MBA from INSEAD and an Engineering degree from Cambridge

    University.

  • Table of Contents

    1. Introduction ............................................................................................................................1 1.1 SIP concepts......................................................................................................................1 1.2 Definition of terms ............................................................................................................ 2 1.3 Where is SIP discussed?.................................................................................................... 5

    2. History ................................................................................................................................... 7 2.1 The origins of SIP .............................................................................................................. 7 2.2 How SIP developed ........................................................................................................... 7 2.3 The return to reality........................................................................................................... 8

    3. SIP applications.....................................................................................................................10 3.1 Telephony........................................................................................................................10 3.2 Instant Messaging (IM)..................................................................................................... 11 3.3 Presence .........................................................................................................................12

    4. SIP deployments....................................................................................................................14 4.1 Existing SIP services ........................................................................................................14 4.2 Interoperating with other protocols .................................................................................. 15

    5. Issues complicating SIP deployment ...................................................................................... 17 5.1 Reliability ........................................................................................................................ 17 5.2 Security ...........................................................................................................................19 5.3 Quality of Service (QoS) and Resource Reservation ...........................................................21 5.4 Scalability ...................................................................................................................... 23 5.5 Accounting ..................................................................................................................... 24 5.6 Privacy ........................................................................................................................... 25 5.7 NAT and Firewall traversal ............................................................................................... 26

    5.7.1 Types of NAT ............................................................................................................. 26 5.7.2 Using SIP through NATs............................................................................................. 28 5.7.3 Application Level Gateways (ALGs) ............................................................................ 29 5.7.4 Devices behind the same NAT.................................................................................... 30

    5.8 Device configuration ....................................................................................................... 30 5.9 IPv6.................................................................................................................................31

    6. SIP and the PSTN .................................................................................................................. 32 6.1 Interoperability............................................................................................................... 32

    6.1.1 Overlap signaling...................................................................................................... 32 6.1.2 Early media............................................................................................................... 33 6.1.3 Application Control with a traditional phone keypad .................................................. 34

    6.2 Regulatory requirements..................................................................................................35

    Copyright Metaswitch Networks. Confidential | Page i

  • Copyright Metaswitch Networks. Confidential | Page ii

    6.2.1 Wire-tapping............................................................................................................. 36 6.2.2 Emergency calls .........................................................................................................37

    7. Enhanced applications for SIP............................................................................................... 39 7.1 Mobile (3G)..................................................................................................................... 39 7.2 Caller preferences........................................................................................................... 40 7.3 Third party Call control .................................................................................................... 40 7.4 Conferencing .................................................................................................................. 42 7.5 Click-to-call or click-to-dial.............................................................................................. 44 7.6 ENUM ............................................................................................................................. 45

    8. The future............................................................................................................................. 46

    9. Further information............................................................................................................... 48 9.1 Web-sites ....................................................................................................................... 48 9.2 IETF RFCs and drafts ........................................................................................................ 48

    9.2.1 Application Control with traditional keypad ............................................................... 48 9.2.2 Early media............................................................................................................... 48 9.2.3 Overlap dialing ......................................................................................................... 48 9.2.4 3G Mobile ................................................................................................................. 49 9.2.5 AAA and security ....................................................................................................... 49 9.2.6 Caller Preferences..................................................................................................... 49 9.2.7 Conferencing ............................................................................................................ 49 9.2.8 NAT and firewall traversal.......................................................................................... 49 9.2.9 Device configuration ................................................................................................. 50 9.2.10 Presence and Instant Messaging ............................................................................. 50 9.2.11 QoS ........................................................................................................................ 50 9.2.12 Other documents .................................................................................................... 50

    10. About Metaswitch......................