Sipphone can not hear user's skype

[mberva]

I installed SFA and entry "exten => 6101,1,Dial(Skype/skype_user)" in extensions.conf .
When sip_user composed 6101 and skype_user answered, the sip_user can NOT hear the skype_user's voice.
Skype_user can hear sip_user' voice.
Why the system only works in one direction?
Thanks

[malcolmd]

That's generally a NAT issue related to the SIP user. If the same SIP user can, from the same location as this trouble, call into Asterisk where your dialplan does a record and a playback and that SIP user can hear the audio, then something else is amiss; but NAT is most likely the problem.

[mberva]

Hi malcolmd,
We don't have a NAT related to the SIP user. Communication between two sip user work fine.
I enabled debug mode and when I answered with SKYPE user I get :
Unable to find a codec translation path from 0x100 (g729) to 0x4 (ulaw)
Is this the problem?

[mberva]

The problem is solved.
Uncomment following line in chain_skype.conf

disallow=all
allow=ulaw

Thanks malcolmd for your replies