The problem is lost gsm connection and needed shutdown/restart:
phone work
make call
wifi connect - not too much from making call
disconnect wifi
phone work
repeat
problem case - 1st connect wifi prior make a call or prior sent sms
phone work
wifi connect
make call - can not, not work gsm
disconnect wifi
phone gsm not work till shutdown/restart
phone work
make call
wifi connect - not too much from making call
disconnect wifi
phone work
repeat
problem case - 1st connect wifi prior make a call or prior sent sms
phone work
wifi connect
make call - can not, not work gsm
disconnect wifi
phone gsm not work till shutdown/restart