Hello Andreas,
sorry for late response.
I set up a network with Virtual Um and multiple
OsmocomBB
phones. They register, they can send and receive SMS
and I wanted to try voice calls.
First of all, it should be noted that voice support in OsmocomBB
is experimental and undocumented. I have been working on GAPK
back-end integration, and it seems you've already found some
branch, but I would recommend to use 'fixeria/audio' instead of
'fixeria/mncc'.
calls can be established, but GAPK is never
initialized and
again, I never see voice data appearing as an MNCC message.
Please check out the configuration examples [1] for mobile app.
There you should find the new 'audio' section, where:
io-target hardware
means that audio I/O (by default) should be handled by the
hardware (i.e. by Calypso phone). GAPK is not enabled by default.
In order to use GAPK based back-end, use 'gapk':
io-target gapk
It probably makes sense to rename 'gapk' to 'alsa', because
at the moment 'gapk' enables both voice playback and capture
using the audio system of the host that running mobile.
I never seem to receive a GSM_TCHF_FRAME-message on
the MNCC socket.
This can also be configured:
io-target socket
In this case GAPK is not used, and all TCH frames are being
forwarded to the MNCC handler 'as-is'.
See [2] commit description for details.
Please also note that audio I/O target != MNCC handler, that
actually implements the Call Control logic. See [3] for details.
[1]
https://git.osmocom.org/osmocom-bb/tree/doc/examples/mobile/default.cfg?h=f…
[2]
https://git.osmocom.org/osmocom-bb/commit/?h=fixeria/audio&id=bdb285450…
[3]
https://git.osmocom.org/osmocom-bb/commit/?h=fixeria/audio&id=22edbf3f8…
With best regards,
Vadim Yanitskiy.