False "Out of coverage" error with 2 SIM cards [Jolla C][4.3.0]

REPRODUCIBILITY (100%):
BUILD ID = 4.3.0.12 Suomenlinna:
HARDWARE Jolla C:
UI LANGUAGE: Russian
REGRESSION: Yes

DESCRIPTION:

I have a Jolla C with 2 SIMs installed for two providers slot1 Russian (Beeline.ru) and slot2 Belorussian (MTS.by). The MTS sim has roaming DISABLED by phone operator and cannot connect to network while in Russia. The Beeline sim is fuly functional. The problem is that I cannot make any voice calls and get “No network coverage” error.

I observe this at a place with 100% coverage of 2G, 3G, 4G and 5G from multiple providers. The phone is simultaneously connected to Internet. It can download files via mobile network, receive calls and sms and still denies all attempts to initiate a voice call. I tried to fiddle with mobile network settings by toggling flight mode, switching to 2G, 3G and 4G modes to no avail. The fully working Beeline SIM sees its network and is set as the default sim.

The second SIM seems to be in constant network search state because its home network is not available. The root of the problem is likely to be wrongful routing of voice calls to the sim which cannot connect.

I was able to circumvent this problem by removing the second MTS sim, but It is a poor solution. I plan to travel to and from Byelorussia in the future and I do not want to lose it.

PRECONDITIONS:

Two installed sims, one of which cannot connect to any mobile network currently availble.

STEPS TO REPRODUCE:

  1. Install your primary SIM and set it as the default in the SFOS settings.
  2. Install a second SIM of a foreign provider which has no roaming support.
  3. Try to make a voice call.

EXPECTED RESULT:

The call should work as usual via the default (primary) sim of your local operator.

ACTUAL RESULT:

You get “No network coverage” error.

PLEASE, add an option to disable a second sim altogether without removing it from the device. Fix, the automatic sim selection so that the dialer would not try to use a sim which cannot connect while ignoring another working sim.

I cannot say anything regarding this bug itself (as it is quite hard to reproduce).
But

this is already there in
Settings - Connectivity - SIM cards

Just tap the lighted dot and the glow disappears and SIM is not in use.

Thanks! The workaround works and the option to disable a sim is there. As for reproducing the bug, I think that any unpaid/old&blocked sim would do.