whose network do T-Mobile phones use?

Makes sense. Virgin Mobile and Sprint are CDMA. AT&T and T-Mobile are GSM.

Check out Net10.com uses other networks both CDMA and GSM and has an unlimited everything package for $45 if you pay on time.

Used tmobile last year with at&t network . Switched to virgin mobile ( sprint) , $55.00 a month for unlimited text, talk and data. No contract!
Sprint service has been better for me. I'm on st Croix.

Coo; thanks for comfirmingl. T-Mobile just announced they are switching to no contracts, and they offer an unlimited data plan. If they're using AT&T's network here, then... why am I paying more for less data with AT&T? Time to check my contract details!

http://www.nytimes.com/2013/04/04/technology/personaltech/t-mobile-breaks-free-of-cellphone-contracts-and-penalties.html?src=me&ref=general&_r=0

Coo; thanks for comfirmingl. T-Mobile just announced they are switching to no contracts, and they offer an unlimited data plan. If they're using AT&T's network here, then... why am I paying more for less data with AT&T? Time to check my contract details!

http://www.nytimes.com/2013/04/04/technology/personaltech/t-mobile-breaks-free-of-cellphone-contracts-and-penalties.html?src ="me&ref=general&_r=0

If you use a smart phone you should check with T-Mobile to see if their Domestic Data Roaming allotment applies in the VI. Since the VI is not serviced by T-Mobile and is listed as provided by a Service Partner.

http://support.t-mobile.com/docs/DOC-3299