Bug #6461
openGSM 04.08 phase 1: Mobile terminated setup messages - octet 3a in case of speech
0%
Description
Some early GSM phones implementing phase 1 specification (here: Siemens P1; S/W version 18.06.93 09:58:48) reject mobile terminated calls from OsmoMSC if octet 3a is present in the setup message.
04.08 v3 states octets 3a (and 4-6) shall only be present in case of information transfer capability != speech (10.5.4.4; PDF page 373).
04.08 v4 states: "If the information transfer capability field (octet 3) indicates "speech", octet 3a etc shall be included only if the MS
supports at least one speech version other than: GSM full rate speech version 1; GSM half rate speech version 1." (10.5.4.5.1; PDF page 293)
With reference to Bug#6459 (OsmoBSC), the classmark 1 IE within location update request indicates if the MS is a phase 1 device. This could be an indication to omit octet 3a in encoding outgoing MT setup requests.
Refs:
https://www.3gpp.org/ftp/Specs/archive/04_series/04.08/0408-3d0.zip (GSM TS 04.08 v3.13.0)
https://www.3gpp.org/ftp/Specs/archive/04_series/04.08/0408-3E0.ZIP (GSM TS 04.08 v3.14.0)
https://www.3gpp.org/ftp/Specs/archive/04_series/04.08/0408-4p0.zip (GSM TS 04.08 v4.25.0)
Specification phases (from #6459):
Phase Freeze Date Spec Versions 1 1991 3.X.X 2 October 1995 4.X.X 2+ never 5.x.x; aka R96 and higher
Files
| gsmts_0408sv031300p.pdf | View gsmts_0408sv031300p.pdf | 11.4 MB | |||
| 0408-4p0.pdf | View 0408-4p0.pdf | 2.71 MB | |||
| picture326-1.png | View picture326-1.png | 145 KB | |||
| picture326-2.png | View picture326-2.png | 96.9 KB |
Updated by nt2mku 25 days ago
Related: https://gerrit.osmocom.org/c/libosmocore/+/36784 - but the encoding should consider the MS specification phase as mentioned above. OsmoMSC could remove all non-phase 1 codec offers for the outgoing call in this case, so octet 3a won't get encoded.
