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CUCM SIP calls disconnect after 15 mins; refresh adj

Level 1
Level 1

I have a CUCM 12.5 installation where PSTN calls (through a Spectrum Enterprise SIP trunk) disconnect after 15 minutes. The CUCM connects directly to the telco-provided Audiocodes Mediant SBC. I do not have a CUBE involved in this setup.

Attached is a call trace. It appears the Spectrum SBC is sending a reinvite at the 15 minute mark and CUCM is responding “trying” but then perhaps never closes the loop? Then the SBC sends a 408 Request Timeout and tears the call down.

I have messed with the SIP refresh timeout in CUCM service parameters both increasing and decreasing it and the problem remains. I am not an expert but to me there must be some setting that can instruct CUCM to send something more definitive in response to a mid-session reinvite than “trying.”

Any ideas where to look?

Many thanks in advance.

2 Replies 2

Cisco Employee
Cisco Employee

I checked couple of calls in the logs, and I noticed that the MRA device side, puts the other party on hold, also you have the MTP option checked on the trunk.

Does the issue happen if:

- MTP not checked

- The other party does not put the call on hold

Also CUCM software MTP does not support T.38, and could cause some unexpected behavior, can you disable this codec from Audiocodes Mediant SBC side?