Audio stops

[roger_roger]

I have a new customer and we're using Yealink T54W phones. After a few minutes of conversation, they lose audio. If they put the call on hold momentarily, the audio comes back in some cases. They have Comcast internet and have installed their own modem and a Linksys route. I have questions the efficacy of the Linksys but they don't want to hear about that. I have many other customers using Yealink phones with no issue. I also have many other customers using Comcast with the Comcast supplied router either by itself or in bridge mode with our own router in place (a real router, not a Linksys toy).

What could be causing this? I suspect the Linksys's NAT tables are getting overloaded but I have no proof. Any pointers to where to look would be appreciated.

 

[hfoster]

If it's timed to be approximately 2, 3 minutes every single time, it's probably NAT issues. Whether it's a misbehaving ALG, or a overactive firewall terminating UDP sessions. Worth checking that SIP ALG is disabled, and if possible to modify the UDP timeout to be a lot higher. Unfortunately you just have to poke around until you find a setting you want.

Sometimes get a bit more joy out of SIP TCP transport, if you're not already using it. Sounds to me it's more the RTP streams being dropped though, so doubtful.