Roaming
Although T-Mobile USA has the smallest native network of all the national U.S. carriers, it has roaming arrangements with a number of regional carriers, such as Centennial Wireless, Dobson, and Unicel, and with the national carrier AT&T Mobility. These carriers predominately provided service using the GSM 850 MHz band, and a dual band phone is required to use both the native and affiliate networks. When roaming on these affiliated networks airtime is deducted from the user's plan, as opposed to at a surcharge, effectively expanding nationwide coverage.[7]
As of 2007, prepaid customers have only restricted roaming privileges.[8]
While international roaming is available to most customers, it must first be activated through customer service. Once provisioned, there is no monthly fee to maintain international roaming coverage.