Problem with sound

Hi,

I took the latest revision of sipXtapi and compiled it successfully with Visual Studio 2005.
When i try to make some calls (direct) with sipXezPhone i don't hear anything. I have tried changing the codecs (Speex, Speex_5, Speex_15 or Speex_24)
but still no sound. When i make a call from another voip application to sipXezPhone it works, but when two sipXezPhones there is no sound.

What could be the problem? Any help is appreciated.

Thanks,
Oliver