SIP study notes


defined as a module in a voip solution, not covers all call aspects like h.323

goal: session management (creating, modifying and terminates voip sessions)

SIP Session management includes 4 tasks:-
– Locating users (SIP address to IP address)
– negotiating capabilities and feature
– modifying sessions parameters during call
– setup and teardown of all users

SIP borrows many familiar internet standards

SDP exchanges capabilities (like h.245)

Key feature: Presence

SIP quickly moving to own industry

Reasons to use SIP:
1. Integrating with other phone systems (SIP Trunks)
2.Multimedia application integration (like IM)
3. easier troubleshooting
4. supporting 3rd party phones on a CCM network

SIP Components
ser agents (Clients and servers)

proxy server – initial point of contact to UAs

Redirect server- finds a location of an endpoint

registrar Server – registers endpoint to DB

Location server – Database of UAs

Presence server – tracks stat of uas

sip messages

method        responce
=======        ==========
Register     Informational (1xx)
Invite        Success (200)
ACK         Redirect (3xX)
Cancel         Client error (4xx)
Options     server error (5xx)
Bye        Global failure (6xx)

1. Phone sends invite nessage to ccm
2. trying (100) message response
3. session progress (183) message response + SDP
4. OK (200) message response ACK
5. RTP stream
6 Bye/OK (200) message

Dial Peers

# show dial-peer voice summary
debug ccsip message

configuring cisco gw as a sip User Agent
registrar ipv4:
registrar ipv4: 789 sec
sip-server ipv4:

session target sip-server

hairpin h.323 to sip

call through to another device

#voice service voip
#allow connections sip to sip
#allow connections h.323 to sip …..

Troubleshooting SIP

Show sip-ua connections
Show sip-ua statistics
Show sip-ua service
debug ccsip messages


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