Dual-SIM not ringing

[S21-User]

Hi,

Since the June update, my dual SIM setup is no longer working correctly. I have been using a German Vodafone and a US T-mobile SIM together for two years and both worked fine. Since a couple of weeks, the phone no longer rings when both SIMs are enabled. I can still make calls without problems and when I use the SIM individually,  they also work.

Neither VF nor Samsung support had any ideas how to fix this problem. I tried a factory reset with no change. When I put the SIMs into my old S10, they work normally. That phone is still on the May SW update.

Please let me know if there are any suggestions. Is there a way to uninstall the last update?

Thanks!

Steve

[S21-Jeff]

I have the same problem. Telekom with US T-mobile. My wife is vodafone with T-mobile. Popping out the sims seems to make it work for a bit, but now I can't rely on any calls coming through. I've told everyone to call me on Whatsapp at this point. Note this is the german version of the phone with the Exnos CPU (SM-991B)

[S21-User]

I also have the German version-SM-G991B. I called Samsung support and they didn't know anything about this issue yet. Please also call to get this on their radar. I'm still under warranty and prefer to a SW patch over shipping the phone in for repair. 

[S21-Jeff]

As an update, got the July update installed and I still have the problem (sort of). Right after booting I was able to get a call, but then I turned on and off do not disturb and then no more ringing. So there is some software bug here.

[S21-User]

Agreed - diasppointing to hear that the July release still has it. I switched my Vodafone # to an eSIM but still have the same issue. Also talked with Samsung support and submitted system logs for debugging. Trying to avoid sending in the phone for a warranty claim since it doesn't sound like they have a fix yet. Please also file a support request via Samsung members so that they hopefully prioritize a fix for the next release. 

[S21-User]

Also received the July update. Looks like it has gotten worse since I now have to restart the phone to get it to receive calls again whenever I change the SIM settings. After a restart with both SIMs enabled, the phone disconnects from both networks on the first incoming call. After it reconnects, the calls no longer come through. Definitely screwed up in the firmware. 

@Samsung #Samsung - is anyone monitoring this forum? Is a fix in the works or do I have to swith to iPhone after all???

[S21-Jeff]

I've pinged samsung support on twitter. So far they jsut say to factory reset even though I pointed them to this thread. No need to go through all that pain if it won't fix the problem.

[S21-User]

Right. I'm still fiddling with the aftermath of the fac reset to get all my apps back to work. Giant waste of time. Let's hope theu now have it on the radar at least for the next release. I haven't heard anything about my service request since a week.

[S21-Jeff]

Heh. I'm told all my contacts to call me via WhatsApp. At least that rings...

[S21-Jeff]

I may have found a workaround... Turning off VOLTE seems to work (for now)