Invalid Mi 9t pro signal for calling problem on 4G

[patospatos]

Hi. I have two days interesting problem. When i have setting in SIM Card set to Prefer 4G network i got no signal message when i want make some call. 4G internet on card is working but no signal for calling. When i set prefer 2G network in setting than signal for calling is OK without problem. Can this be a hardware problem ? Before my calling on 4G working ok in this location and i dont change any other settings.

I am on MIUI Global 12.0.4

thx

 

[sumgyimr]

u need check the 3g single is ok？
if there's no 3g single.
u need check the volte work correct
ur phone need check this option and carrier provider should have this service for user