I am having a problem with one-way audio over VPN. CCM 6.1 with 7940s. Several PIX 501s have a VPN tunnel setup to a central 515E (all on different subnets) and EVERYTHING works perfectly, even the 7940s and voice calls. The problem is that if the phone is not used for a while then a call from another extension results in one way audio. If you hang up and call right back, everything is fine. In fact everything is fine as long as you use the phone on a regular basis but after a couple of hours a call from an extension results in one-way audio again (but for this first call only) and then everything is fine again.
If it was solidly one way audio it would be pretty easy to troubleshoot and fix but you only get one chance a day or so to "catch a falling star". Some clues are that trunk calls (PSTN) via multiple gateways and PRIs (either in or out) always work fine and of course calls to Unity always work fine.
Everything (normal IP traffic) is flawless and you can ping any phone anywhere on the network; we just have this intermittent naging one-way audio problem in one out of 20 calls. I turned off "fixup protocol skinny" at both ends as there is no NAT happening with these calls but it didn't make a difference. Any suggestions appreciated.
Thanks in advance!