Falling asleep on the phone

My long distance boyfriend and I recently started falling asleep on the phone together and we noticed a couple things and was curious if others have had similar issues. If we’ve been on our call for about 8 hours, our call will end on its own. Another thing is if we’ve been on the call for like 5+ hours and I get another call and answer it, it’ll end my call with my boyfriend instead of putting our call on hold like it it usually does (I hope that made sense lol).

Does anybody else have issues like this? I’m pretty sure our phone carriers have a limit of how long we can be on a call for but I do have unlimited talk/calls.

We both live in the US and have AT&T and T-Mobile as our phone carriers.