3G voice broken with ALu 9361 femto
I am trying to create a setup with various Osmocom components to get the Alcatel-Lucent 9361 femtocells I have to function as a small 3G network. Currently, I am experiencing issues with 3G voice calls, quite similar to the ones described in #3411 / #2459 / #1937: the voice call is dropped.
I have traced the issue to the following code: https://github.com/osmocom/osmo-mgw/blob/9aaaab6b3b5a541a6c17077f5f1f8bc00ba77152/src/libosmo-mgcp/mgcp_network.c#L873
The femtocell rejects the IuUP message due to a CRC mismatch and indeed, when the bytes are patched, the header CRC is not updated and therefore cannot match.
Updated by laforge almost 4 years ago
Thanks a lot for your detailed bug report. The lack of proper IuUP support has been
haunting us for a long time. I once started to implement the related state machines
in libosmocore, see the 'laforge/iu_up' branch. However, nobody has yet found the time
or resources to integrate that properly into osmo-mgw and test it :/
Updated by dev_zzo almost 4 years ago
I will be happy to test any updates against my setup. Unfortunately, I am not much of a IuUP expert (I wish I were!) and probably won't be able to help out with development except build/run/verify.
Updated by Vengant over 2 years ago
Would you please share any details about gaining root access to ALu 9361 in order to use it with Osmocom?
Updated by limeanalog almost 2 years ago
I would also like to know how you've connected this to Osmocom? any info would be much appreciated.
Updated by dev_zzo almost 2 years ago
I see there is interest in popping some femtos, glad to see that. Unfortunately, right now I'm a bit overloaded with stuff and can't quite sit down and do an extensive writeup, but I'll try to find some time to do it eventually.
Updated by dev_zzo about 1 year ago
I know this is not a proper writeup and quite a bit late, but I did post some information on Twitter about setting everything up to the point of things somewhat working.
Part 1: https://twitter.com/InfoSecDJ/status/1514348615795421191
Part 2: https://twitter.com/InfoSecDJ/status/1514653111201189897
Part 3: https://twitter.com/InfoSecDJ/status/1515040320186167303
Questions welcome, do free to post them in the relevant Twitter thread.