T-Mobile's 3G network operates on UMTS band IV (AWS), which uses both the 1700 MHz and 2100 MHz bands. This means that your phone needs to support both bands to get true 3G speeds on T-Mobile's USA network. 3G mobile phones sold in Australia generally use the 2100 MHz network, however very few are also compatible with the 1700 MHz UMTS band (some BlackBerry and Nokia phones may support T-Mobile's 3G network). If your phone can't support the 1700 MHz band, it will switch across to T-Mobile's 2G network (which operates at 1900 MHz) and data will be downloaded and uploaded at EDGE speeds. This is not such a major issue as T-Mobile's EDGE data speeds are sufficient for most uses including email, apps, maps and web browsing; however it is not so great if you want to upload and download large files, make VOIP calls (using Skype or a similar service) or watch streaming video. If you need to use these bandwidth intensive applications your best bet is to do this over a free Wi-Fi connection.

In some rural areas T-Mobile may roam onto a network of a partner operator (either AT&T or a small regional mobile service) and they may operate on a 3G band that is compatible with your phone. Unfortunately T-Mobile’s coverage maps don’t tell you when you are on a partner network or at what frequency that network will operate at. Even if a partner network is compatible with your phone, some services (such as data) may not be available to T-Mobile customers. Alaska is one of the main areas where you are likely to be most affected by partner networks.