We're running into an issue where our agents on a third party contact centre system are experiencing 1 way audio on an intermittent basis roughly around the 15 minutes mark.
This is a CUCM v10 solution, connected to said 3rd party contact centre solution via SIP trunks and the customer having SIP trunks into their network for external calls.
We've found that its linked to the SIP session timer expiring and have resolved alot of the issue by increasing the MIN-SE globally to 1800 seconds.
However, we're still experiencing some of these problems.
We have noticed the SIP provider initially sends the external call invite with an expiry of 900 seconds (15 minutes) and we reject with a 422 error saying interval too small, then presumably it gets re-setup with an 1800 SE timer. But on these problematic calls, we do see CUCM send a re-invite back out to the SIP provider (at the 15 minutes mark) and thats when the call goes 1 way audio and the external caller hangs up.
So it potentially seems that some calls might still have this 900 MIN-SE value and its these we're having the problem with.
Anyone experienced this before? Can our CUCM MIN-SE timer be ignored for some calls and some might still have the 900 second value?