I'm looking for a freely available softphone implementation (for research purposes) which provides as many of the following features as possible:
- open source
- codecs defined by e.g. ITU-T, ETSI, ...
- both narrowband and wideband codecs
- playback and recording facilities
Of course I'm aware that there is probably no solution that provides the full desired functionality. But I would appreciate any hints that go at least in this direction.