IP RTP COMPRESSION causes calls to drop

[dschlenzig]

Hi, I've installed a central callmanager with an E1, it has a remote site connected which shares this gateway, it is connected with a 2mb leased line with QoS enabled. I can currently call IP phone (siteA) to IP phone (siteB) with no problems. I can also dial out from both sites with no problem. However if put IP RTP COMPRESSION PASSIVE on the core router and IP RTP COMPRESSION on the remote router I get problems!

Site to site dialling is fine, however if SiteB tries to dial external (over the H323 GW) the call connects but then after 10-30 seconds of working normally there is complete silence, although the call still looks like it's up as the counter on the IP phone is still incrementing. I'm running 12.3.7T1 on all the routers.

Anyone got any ideas?

Rgds, Daniel

[erhoehne]

Unfortunately, there have been many bugs regarding rtp header compression causing various problems with voice calls. I couldn't link your exact issue to an existing bug. However, try disabling the passive portion of the command, and just run rtp on both ends without the passive parameter. If you are already running QOS, then in some cases using rtp will not help much. So, you can try disabling rtp on both routers and see if your voice calls are still as clear.

[dschlenzig]

Thanks for getting back to me, I'll give it a go and see what happens.

Regards, Daniel