I recently switched from AT&T to T-Mobile and one thing I found annoying is that there is always a '1' before the number, indicating it's a US number. Well, I typically only get called from such numbers, so it's not like I need to see that. I didn't have that with AT&T.
This has my phone reading the '1' verbally out loud to me, also has the number when saving as contact to keep the 1, messing up the parentheses look I like for area code. It's mostly aesthetic annoyances, but it has been annoying. T-Mobile said no way to do it. Before I gave up, I wanted to at least inquire about a possible way to have my phone in some way trim off the number from incoming calls. I expect there not to be, but I didn't want to give up without trying.