Network Coverage

I have 4 devices on my account. 2 phones, 1 tablet, and 1 smart watch. I can't make or recieve phone calls, have iffy text message service, and absolutely no mobile data on any device. Half the time when I try to make a phone call I get a message saying my phone isn't registered with a network. The

I can receive direct messages from other iPhone users via iMessage (so direct only). In group chats, I can receive messages from Android users and iPhone users ONLY IF they have AT&T or T-Mobile. I cannot get messages from iPhone users with other carriers in group chat settings (like Verizon or