Calls from a cisco IP Phone out to the PSTN through SIP TRUNK intermittently drop after the call is active for exactly 15 minutes. Which process is failing?
A. SIP Keepalive timeout
B. SIP Dialog Refresh
C. SIP OPTIONS Timeout
D. SIP Expires Timeout
E. SIP Register Refresh
F. SIP Session Refresh
The answer is F. SIP session refresh
https://bst.cloudapps.cisco.com/bugsearch/bug/CSCun31375/?rfs=iqvred
It is actually SIP session expires timer parameter which is changed in the CUCM service parameters and default is 1800 seconds (30 min):
SIP Session Expires Timer: Required Field This parameter specifies the interval between session refresh requests in a dialog. When this timer expires, the session is considered timed out. The UAS obtains this value from the Session-Expires header field in a 2xx response to a session refresh request that the UAS sends. Proxies and UACs determine the session interval from the Session-Expires header field in a 2xx response to a session refresh request that proxies and UACs receive.
This is a required field.
Default: 1800
Minimum: 90
Maximum: 86400
Unit: sec