Re: EFR and AMR voice calls

Hi Sipos, You should have said right away, in your initial post, that your issue was specifically with E1 BTS, as opposed to OsmoBTS or ip.access nanoBTS. To me this part was immediately obvious from the Remote Transcoder Failure cause value (plus having seen your name previously in the context of E1 BTS), but it looks like Neels missed this key detail. In your later follow-up: Thank you for clarifying. :-) Now onwards with your actual problem: let us split it into EFR and AMR, i.e., address each of these newer-than-FRv1 codecs separately. For EFR, this patch will probably get you closer to working state: https://gerrit.osmocom.org/c/osmo-mgw/+/39477 To be absolutely clear, it is _not_ a Truly Proper fix - and furthermore, the Truly Proper fix I wish to implement (TFO transform per 3GPP TS 28.062 section C.3.2.1.1 for EFR codec) is still very far away, given the current state of my priority queue. However, it should get you closer to a working state: with the above patch, you won't be getting the Remote Transcoder Failure indication from the BTS, i.e., the BTS will be kept happy in terms of what it sees on E1 Abis downlink. It is the best we can do on a short time scale. (And yes, I spent today doing this patch series specifically because I felt prompted by your experience of running into this bug.) See trau_frame_up2down() function in libosmo-abis (very deprecated code, but still present in mainline libosmo* suite) - I never played with the old OsmoNITB (I joined Osmocom well after the split), but I reason that old TRAU code must be what the old OsmoNITB used. Needless to say, it is nowhere close to what we need in terms of a proper TFO transform. I invite you to watch the video of my most recent OsmoDevCall presentation on this topic (2025 Jan), and/or look at my posted slides from that talk. Now onwards to AMR. Here the situation is simpler: OsmoMGW-E1 does not support AMR at all. Furthermore: * The work to add AMR support for E1 BTS would need to begin in the libraries (libosmotrau in libosmo-abis.git) before tackling the application, as in OsmoMGW-E1 or a wholesale replacement; * Experimentation will be needed with specific E1 BTS (Ericsson RBS6k in my case, or Nokia MetroSite in your case) to see if the BTS can handle the behaviors of TS 26.094 section A.5.1.2.3 (accept SPEECH_BAD, SPEECH_DEGRADED, SID_BAD and NO_DATA frames in DL) _without_ involving BTS-controlled TFO-AMR. Again, please refer to my TFO presentation. HTH, M~