Dear Mychaela, Thanks for the detailed explanation, I already watched your presentations in the past, yet I was completely unaware that the E1 based MGW has different capabilities.
I am happy to confirm that your recent Osmo-MGW patches indeed fixed the EFR call, which now works as expected. I wonder if this also means we can connect EFR calls through the external MNCC or the sip-connector to a PBX or that is still FR only for E1 based BTSes? I have and EDGE capable MetroSite with the latest SW ever released for them, which means full AMR support, so once you have something I can give it a try, can provide captures, logs, whatever you need. I wonder if a similar "hack" with AMR could work, lets say for the normal 12.2 AMR-FR calls (without fallback and other perks). Regards, Csaba Mychaela Falconia <[email protected]> ezt írta (időpont: 2025. febr. 6., Cs, 0:52): > > Hi Sipos, > > > FR calls between mobile phones are working fine, but when I change the > > codec-list to > > "codec-list fr2 fr1 fr3" or "codec-list fr3 fr1 fr2", I am getting a > > Remote Transcoder Failure: > > > > lchan(0-0-1-TCH_F-0)[0x630d01c78b80]{ESTABLISHED}: (type=TCH_F) > > CONNECTION FAIL (cause=Remote Transcoder Failure [ 28 ]) > > 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: > > > This test was on a Nokia InSite (which can only do FR/EFR), I also > > tested it on MetroSite with full AMR capability and it is the same > > issue (both EFR and AMR calls fail the same way, FR works as > > expected). > > 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.) > > > I am fairly sure with Osmo-NITB at least EFR was working with these > > phones and BTS some years ago. > > 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~
