Hi Vikram,
See below for
SIP
https://supportforums.cisco.com/document/113271/understanding-sip-traces
https://supportforums.cisco.com/document/71131/basic-sip-call-flows-troubleshooting-commands
MGCP
http://www.cisco.com/c/en/us/support/docs/voice/media-gateway-control-protocol-mgcp/44130-understanding-mgcp.html
http://flylib.com/books/en/2.285.1.27/1/
http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cata/186_188/3_0/english/administration/guide/mgcp/mgcp30ad/mgcpaaph.html
SCCP
http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cata/186_188/2_15_ms/english/administration/guide/sccp/sccp/sccpaaph.pdf
H323
https://supportforums.cisco.com/document/12560966/h323-call-flow
http://ccievoicehopeful.blogspot.in/2012/09/h323-notes.html
(Rate if it helps)
JB
