I need an application that can receive a call through SIP (Can use any sip stack like sipdroid) and forward it to the GSM network. The application should then forward the audio and convert from SIP to GSM and vice versa.
The app should be able to run on cheap devices (+-100$).
I was thinking on a way to emulate a headset and set it as default, so just need to initiate a call on gsm network using core android functions and audio will be automatically forwarded.
Codecs: Minimum g711, desired g729.
Also except good sound quality without any latency.
Please contact me if any opinions or recommendations.