Bug #6152
openbuilt-in MNCC: forward the @Low layer compatibility I@ IE to the called subscriber
50%
Description
The Low layer compatibility I
IE is usually present in mobile-originated (CC) Setup messages related to date calls (CSD). According to 3GPP TS 24.008, section 9.3.23.1.7, this IE shall be included in the mobile-terminated (CC) Setup message if the calling user specified it. Currently this IE is simply ignored by the built-in osmo-msc's MNCC and not forwarded to the called party.
Files
Related issues
Updated by fixeria 8 months ago
- Related to Feature #4394: Circuit Switched Data (CSD) Support in osmo-msc added
Updated by laforge 5 months ago
jolly wrote in #note-4:
Patches prepared, but not yet pushed to Gerrit.
I have no phone to test it.
This is sad, adn we should make sure you have some devices that speaks CSD. Will look into that, but that will take some time.
Unrelated to the above, we generally want to have automatic test coverage, so a TTCN3 MSC test for MO and MT csd should verify the LLC is passed through transparently on MO and MT.
Updated by fixeria 5 months ago
laforge wrote in #note-5:
This is sad, adn we should make sure you have some devices that speaks CSD. Will look into that, but that will take some time.
AFAIU, the problem here is that jolly has no phone that would include the Low layer compatibility I IE in MO SETUP.
I do have a few (Calypso based SE K200/K220 definitely does include it), so I could do some testing if I had patches.
Unrelated to the above, we generally want to have automatic test coverage, so a TTCN3 MSC test for MO and MT csd should verify the LLC is passed through transparently on MO and MT.
We do have TTCN-3 test cases verifying MO and MT data calls in ttcn3-msc-test:
- TC_lu_and_mo_csd,
- TC_lu_and_mt_csd.
We can extend those to verify forwarding of the LLC/HLC IEs, but I would go for adding separate testcases for this ticket (re-using the existing code).
Also, some time ago I worked on adding TTCN-3 testcases for osmo-msc, testing MS-to-MS voice and data call with the built-in MNCC.
Currently we only test either the MO or the MT signalling with external MNCC, but not with built-in MNCC.
I will find that WIP code and push it to a branch.
Updated by laforge 5 months ago
On Tue, Dec 19, 2023 at 04:31:26PM +0000, fixeria wrote:
Currently we only test either the MO or the MT signalling with external MNCC, but not with built-in MNCC.
I will find that WIP code and push it to a branch.
yes, that would make sense to have tests covering built-in mncc.
Updated by fixeria 5 months ago
fixeria wrote in #note-6:
I do have a few (Calypso based SE K200/K220 definitely does include it), so I could do some testing if I had patches.
Please find a PCAP attached. The The Low layer compatibility 1
is sent by the calling phone (in frame 125) and being forwarded to the called phone (in frame 197), as expected.