[cisco-voip] UC520 one way audio

[Anthony Kouloglou]

Hi all,
i have a UC520 running 124-11.XW2 and 7940s running 7.2(T0.23).
The UC520 has 1 BRI VIC.

Sometimes, during a call of an inside ipphone user with a user outside 
the UC520 (after 5 minutes or so) the outside user stops hearing the 
ipphone user but the ipphone user continues to hear the other party.
The only solution is to hang up.
What do you suggest i should debug and how? It seems really random...
I have to possibility to log anything i want in a server.

Thanks
Anthony