Session Initiation Protocol (SIP)

Speaker: Yuan-Po ShenDate: 2012/07/16

What Is SIP?

• A signaling protocol – Create, modify, terminate a multimedia session

• For Voice over Internet Protocol (VoIP) communication, use port 5060

• Defined in RFC (Request For Comments) 3261• A client-server architecture– User Agent Server (UAS)– User Agent Client (UAC)– User Agent (UA) = UAS + UAC

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What Is SIP? (cont’d)SIP addressing (Uniform Resource Indicator)

sip:Sampo@10.21.21.197(SIP-URI)sip:Sampo@[2001:e10:6840:21:20c:29ff:fe13:b1d]

SIP request methodsREGISTER, {INVITE, BYE, CANCEL, ACK}, OPTIONS

SIP request syntaxINVITE Sampo@10.21.21.197 SIP/2.0

SIP response status code 100 Trying, 200 OK, 302 Moved temporarily, 403

Forbidden

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What Is SIP (cont’d)

• Work with – Session Description Protocol (SDP)• c = connection information, ex: c = IN IP4 163.22.21.194• m = media description, ex: m = audio 7078 RTP/AVP 0 • a = media attribute, ex: a = rtpmap:0 PCMU/8000/1

– Real-time Transport Protocol (RTP)

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SIP SDP

RTP

SIP Call Flow (UA to UA)

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Three Types of Server

• Proxy server– Accept requests/responses and forward them

onward

• Registrar– Provide a server with an address at which the user

can be reached for SIP sessions

• Redirect server– Response with a alternative contact address

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Can be installed on the same device

Proxy Server

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Registrar

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Redirect Server

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SIP Call through Proxy Server

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Conversation

Call Forking

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INVITEINVITE

INVITE

OK

OKCANCEL

Conversation

SIP - Instant Message (IM)

• Defined in RFC 3428 • MESSAGE method

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References

• http://xms.ipv6.club.tw/xms/index.php?view=content_show&id=1015 2009 lab orientation session

• Daniel Collins, “Carrier Grade Voice over IP,” McGraw-Hill, September 2002

• “Session Initiation Protocol,” IETF RFC 3261, June 2002

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X-Lite / Linphone

X-Lite

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Show Menu

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Account Setting (cont’d)

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Account Setting (cont’d)

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Account Setting (cont’d)

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Register Successfully

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Make A Call

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Terminate A Call

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Send Instant Message

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Send Instant Message (cont’d)

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Linphone

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References

• http://www.counterpath.com/assets/files/191/X-Lite3.0_UserGuide.pdf X-Lite user guide

• http://www.linphone.org/index.php/eng/getting_started Linphone startup guide

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Exercises

1. 分別以 IPv4透過 X-Lite註冊以及使用 IPv6透過 Linphone註冊 SIP Server:

1. IPv4:10.21.21.1972. IPv6: 2001:e10:6840:21:20c:29ff:fe13:b1d

2. 通話並且用Wireshark抓下封包觀察封包內容

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• http://voip.com.ncnu.edu.tw/Summer2012/sip/oi_x-lite_win32_41_63214exe.exe

• http://voip.com.ncnu.edu.tw/Summer2012/sip/linphone-3.5.2-setup.exe

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