SIP Timers: What is use of TimerC in SIP?

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RFC-3261 doesn't talk much about TimerC and when it fires. I understand the importance of TimerC in forking scenarios.

Does TimerC have any role in regular SIP call?

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jeand On

Correct. Only Proxies use Timer C. Timer C is the proxy INVITE transaction timeout. It is used to check if a proxied INVITE request never generates a final response. The Timer C MUST be set for each client transaction when an INVITE request is proxied ie each URI you forward the SIP INVITE to after receiving the initial INVITE.