I try to use sys.callback("123456@provider", "234567@provider") to make callback, incoming call is fine, but just can't hear any ringtones, and when the other side pick up the phone, still no voice on the caller side.
I tried to use ideasip, pennytel, it both like this, when ideasip, both side no voice, when use pennytel, the callee can hear the caller's voice, but caller side can't hear anything.
no voice in callback
Re: no voice in callback
The Callback method relies on provider supporting a particular SIP mechansim called re-INVITEs and unfortunately not all of them do. Other people have had the same issue with different providers. The key to getting the Callback to work is trial and error with different providers or SIP devices to find a working combination.