If you have a GSM phone and are roaming where GSM is available you can often buy a local ‘chip’ and have local service for very cheap (don’t know specifically for dubai though). Iirc all of TMobile phones in the US are GSM so this should have been possible for her.
Yeah, i did that for my daughter who is doing study abroad in Italy. The charges are way way lower then the ATT overseas rate. We did have to unlock the phone however.