Bug #4153


3G voice broken with ALu 9361 femto

Added by dev_zzo over 4 years ago. Updated over 1 year ago.

Target version:
Start date:
Due date:
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Spec Reference:



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:

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.

Actions #1

Updated by laforge over 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 :/


Actions #2

Updated by dev_zzo over 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.

Kindest regards,

Actions #3

Updated by Vengant almost 3 years ago

Hi dev_zzo,

Would you please share any details about gaining root access to ALu 9361 in order to use it with Osmocom?

Actions #4

Updated by limeanalog over 2 years ago

Hi dev_zzo,

I would also like to know how you've connected this to Osmocom? any info would be much appreciated.

Actions #5

Updated by dev_zzo over 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.

Actions #6

Updated by dev_zzo over 1 year ago

Hello all,

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:
Part 2:
Part 3:

Questions welcome, do free to post them in the relevant Twitter thread.


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