I suppose anything is "possible" no matter how improbable. Further, I suppose we could have requested additional information about the type of spare phone, technical prowess of the parties and their willingness to deal with a dual mode international device if indeed that is what they possessed.
OP's question was, "I have an extra sprint phone, is it possible for him to temporarily use this phone until he is able to get a new at&t phone?" (italics added by me for emphasis.) My response simply answers the question. Yes, it is "possible."
Yeah, but it didn't sound like they wanted to "make something work" rather just wanted to hand a Sprint phone to BF and have him activate it on AT&T. I have a world phone from Sprint too and while it works well overseas getting it on T-Mobile & AT&T as annoying.
Actually, it depends on what model phone you have. Several of Sprint's international phones with SIM slots can be used on ATT (with minimal research). For example, Photon, Touch Pro 2, Intrepid and BB Tour (talk/text) can be modified to use on ATT. Google is your friend.
What she needs is a used AT&T phone. She can go to cowboom.com (bestbuy's refurb remarketing site) and look for used AT&T phones. Either that or ebay. condition and quality are hit and miss but the price is right.
You can also check your local craigslist to see if someone has a used Sprint phone for sale. You won't have to pay an activation fee if the phone has a clear ESN and was previously used on Sprint. You can activate it online yourself.
sprint is using different system and it is so impossible to use sprint phone on other carrier; so, sprint system will never recognize the serial number of other carrier's phone and the other carrier's system will never recognize sprint phone; your boyfriend can get options by calling his local carrier's support hope this helps
Sprint and AT&T use different wireless technologies, so a Sprint device will not work on the AT&T network and vice versa. Sorry!