Cellular Network Infrastructure » Radio Access Network » OsmoBTS

Not sure if it's osmobts or openbsc to blame but in following setup there's 1-way audio:

ms1 <-> sysmobts <-> openbsc <-> nanobts <-> ms2

The audio ms2 -> ms1 can be heard (if -P option is used for openbsc than some stattering in voice is audible, not sure if it's a separate issue) but the audio ms1 -> ms2 is nonexistent. In some test 1-2 words could be heard before audio is gone. Switching phones change nothing.

OpenBSC is configured for full-rate channels with AMR codec in the attached .pcap although the same effect could be observed with other codecs too.