Zuk Z2 call not sent


New Member
Sep 13, 2018
I am facing a problem with my ZUK Z2. After removing the second sim card I am not able to do any calls. My signal strength is fine the sim card is fine (already tried a diffrent one) and I have tried if the problem is solved when I reinsert the second sim card as before but it's still the same problem. The error "call not sent" occurs everytime. I have already tried to reset the network setting and rebooted multible times, google wasn't helpful either.
Whenever I get called, I see it on my display and I can accept the call, however I can't hear the other one and the other can't hear me.

Do you have any idea how I could fix this without wipeing the whole data or to factory reset the phone?