Chan_mobile one way voice with Galaxy S5


I am running Asterisk 13.11.2, and setup chan_mobile to pair a Samsung Galaxy S5 via a D-link BT adapter to a Devuan 1 which is a version of Debian Jessie.

The phone successfully pairs with Asterisk and Incoming calls on the mobile will ring the house phones via a SIP connection using a “simple bridge”:

== Using SIP RTP CoS mark 5
– Called SIP/2201
– SIP/2201-00000007 is ringing
– SIP/2201-00000007 answered Mobile/SAMSUNG-SM-G900A-bdd4
– Channel SIP/2201-00000007 joined ‘simple_bridge’ basic-bridge
– Channel Mobile/SAMSUNG-SM-G900A-bdd4 joined ‘simple_bridge’ basic-bridge

The issue I am experiencing is 1 way voice from the Mobile to the SIP ATA. Voice from SIP ATA via Mobile to far end works fine, but I cannot hear the far end voice on the house phone.

I can however hear DTMF tones from the far end.

I spent a number of hours digging into chan_mobile and doing some Bluetooth sniffing (using btsnoop on the phone) by comparing the connection to a HandsFree connection to my car and the difference I see is that the car declares itself as an “audio sink”.

I am not (yet) a bluetooth expert but Google seems to imply that the car is using the Bluetooth A2DP profile as well as the HFP profile. I know that A2DP is really for streaming audio but that is the only thing I can think of that would account for the one way voice (ie. the phone is sending the voice over A2DP while the DTMF are sent over HFP).

Anybody have Bluetooth/bluez expert advice on whether this is a plausible theory?

Any information on whether adding A2DP to either the bluez config (/etc/bluetooth/audio.conf) or adding A2DP directly into chan_mobile so I can test would be appreciated.

I have never programmed the bluez API, but am learning.