Hello,
the s700i can be easily configured to use tzones on tmobile.
simply visit tmobile's online configurator and send the settings to yourself. you wont find s700i listed in the model drop down box, but I suspect that if you select the k500i that the settings for it are the same so they should work on your s700i.
https://secure.mouse2mobile.com/clients/tmobileUS/ota_support/
good luck!
--Corey