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4 comments:

• Commit Message:

  • Patch Set #2, 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.

    Done

    Not addressed.

• Patchset:

  • Patch Set #7:

    In my opinion, this patch is trying to solve the wrong problem, or trying to solve the problem in th […]

    @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.

  • Patch Set #7:

    Let's ensure test stability: […]

    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:

  • Patch Set #7, Line 4:

    @fixeria I see you added a test that expects 3a to be omitted.

    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
    ```

    Is this 3a omission according to 3GPP specs?

    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.

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