2 Carriers on Unlocked Phone

A friend asked me this question and I didn't know the answer. He has Red Pocket AT&T. He has to work in a location that has good Sprint coverage so he wants to get another plan on Red Pocket Sprint.

He wants to carry around only one phone.

His Red Pocket AT&T is in an unlocked Android that works with all carriers. If he gets Red Pocket Sprint, will he be able to switch and use the two SIM cards using just his current unlocked Android phone?

He asked me and I didn't know whether Sprint SIM cards lock up a phone to Sprint even if it is an unlocked phone. I have heard something about a phone and a Sprint SIM card being wedded to each other. Will he have to swap out his phone after every time he uses Sprint and before he puts in his AT&T SIM?

You can swap between the two sims on the one phone that is fine. You aren't locked to sprint.

(However the sprint sim is married to the phone so you can't swap it to a new phone and expect service without reactivating)

Good to know. This will work out good for him.

Personally, I don't like swapping SIM cards. Too much hassle IMO. I put a case on all my phones and find it a PITA to get the case off, open the phone, swap the SIM card, then do the whole rigmarole once again when I need to swap again. Too much trouble for me. I'd rather carry two phones than do this dance every time.

It seems when you put a phone on Sprint, it seems they FED lock your phone for 50 days then you have to call to unlock it. FED lock prevents you from using the phone with a Sprint-based MVNO. It's unscrupulous, especially when you bring in an unlocked phone. Now that Sprint is no more, I wonder if T-Mobile is doing this to its customers still using Sprint SIM.

Yeah, that practice is down right wrong and should be illegal. For the case of the OP, that may very well be what stops him/her doing the SIM swaps as needed.