Some quick notes on troubleshooting tools in a Cisco SIP Call Manager environment:
Commands on the CUBE router:
show call active voice compact
debug ccsip messages
debug voip ccapi inout
Article on understanding SIP traces:
https://supportforums.cisco.com/document/113271/understanding-sip-traces
SIP call flows and troubleshooting:
https://supportforums.cisco.com/document/71131/basic-sip-call-flows-troubleshooting-commands
Using CUCM RTMT Session Trace:
http: