Description of problem:

Empathy client connected to a SIP provider (with a telephone number and PSTN connectivity) often drops calls in the middle. After that, it often refuses to reconnect (it's usually able to call another number). I know from the callee that he was not trying to call back.

There's no hint about the reason why empathy/telepathy fails

On the same network, a hardware phone works without problems.

Version-Release number of selected component (if applicable):

empathy-3.0.1-3.fc15.x86_64
telepathy-sofiasip-0.7.1-2.fc15.x86_64
sofia-sip-1.12.10-6.fc15.x86_64

How reproducible:

Sometimes

Steps to Reproduce:
1. Do many SIP calls with Empathy