If you have a T-mobile BlackBerry, it is easy to get frustrated when you enter an area without service. T-Mobile, as one of the newer entrants in the wireless business, has a network that isn't necessarily as broad as other carriers? networks. For the savvy user, there is a little-known 'secret? that can provide much wider coverage, however. Thanks to roaming agreements between T-Mobile and Cingular, T-Mobile users can log on to the Cingular network at no additional charge and use it if there is no T-Mobile coverage.
Accessing the Cingular network may take a bit of practice to do correctly, but it could be worth it if you need to be out of T-Mobile's coverage area for a long period of time. Here is how it works: Go to the "wrench" or 'tools? section on the BlackBerry screen then choose ?Network? on the menu. Change the settings from ?automatic? to ?manual? and then 'scan for networks.? If a Cingular network shows up, select it. You might get warned (we don't know why) that it is only available for "emergency calling" and be asked if it is ?okay.? Select ?yes.? Tah dah! You should have coverage for both voice and data and at no additional cost thanks to T-Mobile's roaming agreement with Cingular. The only catch appears to be that after a number of hours the process might need to be repeated.
Source: Telecommunications Research and Action Center: trac.org