Asterisk - Codec Pb?


I am facing some problems with my asterisk server

Apparently, it works fine.
The server got a connection to a VOIP provider
Phone A is register to aVOIP provider
Phone B has 2 accounts ( Voip Provider - Asterisk server )

If Phone A called Phone B ( linked with the same provider -> Fine )
If now, Phone A calls Phone B ( Using it’s Extension )
=> the communication is like talking into Water or into a Tube !??!?!?!?
Both are using Alaw codec.

I really think that the problem is linked to an RTP/QOS or Router problem
Sounds to be a Codec probelm…

  • Any idea what could be the problem ? ( As well. via extension, the volume is much louder :frowning:

Thanks for your help