Two SIM cards - can't answer calls (both turned on)

I have the following issue: I have two SIM cards activated. When I want to answer an incoming call, the call is immeditely interrupted.

What works is to decline a call (“busy” sound for the caller).
But whenever I click on “answer” (or “accept”), it seems that the call starts for a short moment and then hangs up.

There is no difference, which SIM is being called (before a restart it worked for SIM 2) and whether the FP2 is in sleep or wake mode.

I also checked the GSM settings: no redirects set.

Finally I tried with several different dialers but the issue remains.

Does anyone experience(s/d) the same? Is there anything I could try?

Thanks

3 posts were merged into an existing topic: Two SIM cards - can’t make calls when both are turned on