A workaround for this is to downgrade to Asterisk 11.
I have set up RasPBX on a Raspberry Pi 1 using chan_mobile to forward calls to and from a mobile phone to a SIP client using the both the instructions for plain Asterisk here and via FreePBX here. In both cases outgoing calls (from SIP client via mobile) work fine but on incoming calls (to mobile forwarded to SIP client) the caller can hear the receiver but the receiver cannot hear the caller. A found a post with a similar issue that suggested to force USB to 1.1 using the dwc_otg.speed=1 boot option...
I know this is an old thread, but ... https://jtanx.github.io/2016/02/24/using-asterisk-to-route-calls-through-mobile/ https://pbxinaflash.com/community/threads/chan_mobile-and-bluetooth-with-piaf-reliable.16533/
Get the zip from the master branch of the pantheios repo on github [1]. It has the...