Calling and connectivity issues

Actually from my iPhone 11 so many times I am unable to call and it shows call failed. Some phone numbers I can’t dial but from the other person’s phone I can dial with the same carriers!!!

sometimes while watching the video I am unable to pause the video and after getting call so many times it happened that I was unable to resume the video.

calling with alternative sim is honestly pathetic!!! We don’t get options in the first go from which sim we would like to make calls!!

any help for it??