Call terminated while voicemail message is being left

[michael.armstrong]

I've had one user complain that calls are being terminated while the caller is leaving a voicemail message. This has happened mostly on incoming calls, but happened once on an internal (single-cluster, no WAN) call. She says termination occurs after about 5 seconds. I'm going to check CDR records now and will post results. I have a vague recollection this has happened before, but I can't find a TAC case or message I've posted in the forum. Now running CCM 4.1(2), Unity 4.0(4), Exchange 2003, but the previous case(s) occured prior to the upgrade from CCM 3.3(3).

[Hin Lee]

Taking a stab here:

Could it be bug CSCdw62748 V-mail will be cut off after 40sec if call via MGCP gateway? The workaround is to add

"no mgcp timer receive-rtcp"

[michael.armstrong]

No, we're using an H.323 gateway. I had a vague recollection last night that it was an issue with the TSP. We upgraded Unity to 4.4(4) with CCM 3.3(3), and had to revert from 7.0.4 to 7.0.3b. In that case, the failure occured on all calls. Now it's intermittent.

[michael.armstrong]

Here's the solution to our problem, FWIW: It turns out that a Unity Registry key (RTPPortBase) somehow (sinister forces, maybe) got set to zero. As the name implies, this appears to be a base address for Unity to use to assign UDP ports to incoming RTP streams. This value is incremented by 2 for each new stream, until RTPPortBase+28 has been used, at which point the cycle starts over again at RTPPortBase. (All this is guesswork on my part, gleaned from examining Ethereal traces. I suspect this value may be different in larger installations.) Thus, in our case, every 14th message failed, since Port 0 is apparently ignored or otherwise invalid. I have no idea how RTPPortBase came to be set to 0, or how long it's been that way. TAC advised setting it to 0x5910; that fixed the problem.