4G calling: Strange behaviour for sim.de

Continuing the discussion from VoLTE provider support:

I have a strange behaviour:

Sailfish OS
Country: DE
Provider: sim.de (uses O2 network)
Device Model: Xperia 10 II
Date tested: 2023-11-08
Registered: ✓
Voice In: ✓
Voice Out: no
SMS in: ✓
SMS out: no

Registration works flawless as well as incoming calls. Outgoing SMS are not sent. Outgoing calls hang up immediately after connection.

However, if I disable “4G calling (beta)” (keeping “Prefer 4G” active) outgoing calls work fine now, sending SMS too. But in this case incoming calls are rejected without ringing.

Thus, for making a call I have to switch off the 4G calling before. After finishing I have to switch on the 4G calling again. If I forget the latter, I will miss all incoming calls.

Is there a way to disable 4G calling automatically before dialling and enable it after the call is finished? Or is there another solution for this problem?

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Can you please confirm that you actually stay on 4G when being called?

Have you checked this thread?

Could it perhaps be a case of no specific config for this virtual provider… and maybe “stealing” O2’s could work?

Yes, when I receive a call, the 4G icon is still present.

When I call a mobile number of another phone, however, the other Phone starts ringing. Then the call breaks down. Sometimes after the first ring tone, sometimes immediately after accepting the call by the other phone. In every case my mobile is deregistered from 4G and my mobile even starts to search the mobile network anew. It takes a while to reconnect the network sim.de and another while to reregister 4G. This phenomenon I established with a few other mobiles from my friends.

Another strange thing I noticed now: When I use my mobile to call my landline number (it is a sipgate number), the call works flawless. In this case the 4G keeps active on my mobile.

What’s this: “stealing” O"'s?

Slow fingers… it should read “stealing O2’s [config]”.

Did you look at that other thread?

You mean those phones work like this too? The it sounds more like a network problem…

Thanks for the hint to the thread.
Yes, seems to be ok with respect to the thread. The tef_o2 firmware seems to be the appropriate one.

  • the getprop … command gives S77.1
  • the content of the S77.1 is mcfg_sw/generic/euro/tef_o2/vlvw/de/mcfg_sw.mbn
  • the firmware file is present in the firmware_mnt directory

The phones of my friends I meant these are the phones I tried to call from my phone with the result that the call breaks. And my phone deregisters from the network. Of course, it could be a network problem. But it is strange that calling my landline number works fine.