Sending and receiving TCH frames with 'mobile'

Hello List, as part of my research, I'm trying to use the 'mobile' app to send and receive data on traffic channels. That is, I want to replace the audio stream from the phone's microphone/speaker by something else supplied by the computer attached to the phone. I realize this feature isn't fully implemented in osmocom-BB currently, and I'm willing to write some code to make it work (and share my results with this list if there's any interest). Here's what I've done so far: - merged the sylvain/traffic and jolly/voice branches - added some code to mobile that writes the payload of downlink frames to a user-specified file once a call has been established As far as the receiving end goes, this seems to work. I'm still unclear as to where I should start on the sending side -- I do expect it to be somewhat more complex. Any pointers -- or a rough outline of what is left to be done to make this work -- would be much appreciated. Kind regards, Michael Voelske