minimal bandwidth codecs missing in android version (f-droid)

[bar-g]

From searching the baresip issues, baresip seems to provide config file options to enable codecs that allow to reduce baresip's bandwidth requirement and provide compatibility with more low- and minimal-bandwidth sip clients.

Particularly:

#module			codec2.so
#module			ilbc.so

[ The speex codec is not among the listed options, but could still be superior to opus at the low bandwidth end, and is able to work at even lower bitrates then opus:
https://en.wikipedia.org/wiki/Opus_(audio_format)#/media/File:Opus_quality_comparison_colorblind_compatible.svg ]