[S] Change in libosmocore[master]: gsm48_encode_bearer_cap(): omit octet 3a if only GSM-FR/GSM-HR v1 is ...

Attention is currently required from: falconia, neels, nt2mku. fixeria has posted comments on this change. ( https://gerrit.osmocom.org/c/libosmocore/+/36784?usp=email ) Change subject: gsm48_encode_bearer_cap(): omit octet 3a if only GSM-FR/GSM-HR v1 is supported ...................................................................... Patch Set 7: (4 comments) Commit Message: https://gerrit.osmocom.org/c/libosmocore/+/36784/comment/4c5a9250_1ed48960 PS2, Line 9: Some early GSM phones (like the Siemens P1 Porty) do not accept a mobile-terminating call setup if octet 3a is present. If speech version is GSM-FR (v1, 0x00) only, omit octet 3a. Not addressed. Patchset: PS7: @falcon@freecalypso.org thanks for your analysis! What you suggest sounds like the most reasonable approach to be implemented on the network side (`MT SETUP`). Though, we may still want this patch to be merged, since it's making encoding of the `MO SETUP` more in-line with 3GPP TS 24.008. PS7: If we go for the Mychaela's proposal, then there would be no need to add new API nor any config parameters. I always thought that including the `Bearer Capability IE` in MO SETUP for a voice call allows to negotiate the resulting voice codec, and the called MS can include an alternative `Bearer Capability IE` in `MO CALL CONFIRMED` message, but this does not seem to be the case and only applies to data calls? File tests/gsm0408/gsm0408_test.err: https://gerrit.osmocom.org/c/libosmocore/+/36784/comment/6878a6c1_2fc16610 PS7, Line 4: For the record, we're talking about this commit: ``` commit 95fc8ea0564e0e146ea672f0a884e262461f6c2a Author: Vadim Yanitskiy Date: Sun Jul 3 05:41:02 2022 +0700 gsm0408_test: add a testcase for gsm48_decode_bearer_cap() ``` There was a follow-up commit by Mychaela Falconia fixing parsing (but not encoding): ``` commit 605c9e63bb0db9c86bde06fd504d25e0969b0130 Author: Mychaela Falconia Date: Sun Jul 3 05:15:30 2022 +0700 gsm48_ie: fix parsing of Bearer capability IE without octet 3a ``` Yes, it's a valid encoding as explained in 3GPP TS 24.008, which is mentioned here several times (both in COMMIT_MSG and code). Let me quote it here again: ``` /* According to 3GPP TS 24.008, section 10.5.4.5.1, octet 3a etc. shall be included only if the mobile station supports CTM text telephony or if it supports at least one speech version for GERAN other than V1 (FR or HR). */ ``` Note that the two commits I mentioned here are addressing the MO BCap decoding problem on the network side, while the present patch is addressing MT BCap decoding problem on the MS side. -- To view, visit https://gerrit.osmocom.org/c/libosmocore/+/36784?usp=email To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: libosmocore Gerrit-Branch: master Gerrit-Change-Id: Ia09abb32a8458384151a6ae28744835ea440fc5b Gerrit-Change-Number: 36784 Gerrit-PatchSet: 7 Gerrit-Owner: nt2mku <degrunert.web(a)googlemail.com> Gerrit-Reviewer: Jenkins Builder Gerrit-Reviewer: fixeria <vyanitskiy(a)sysmocom.de> Gerrit-Reviewer: neels <nhofmeyr(a)sysmocom.de> Gerrit-CC: falconia <falcon(a)freecalypso.org> Gerrit-CC: pespin <pespin(a)sysmocom.de> Gerrit-Attention: falconia <falcon(a)freecalypso.org> Gerrit-Attention: neels <nhofmeyr(a)sysmocom.de> Gerrit-Attention: nt2mku <degrunert.web(a)googlemail.com> Gerrit-Comment-Date: Tue, 28 May 2024 21:21:35 +0000 Gerrit-HasComments: Yes Gerrit-Has-Labels: No Comment-In-Reply-To: falconia <falcon(a)freecalypso.org> Comment-In-Reply-To: neels <nhofmeyr(a)sysmocom.de> Comment-In-Reply-To: fixeria <vyanitskiy(a)sysmocom.de> Gerrit-MessageType: comment