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I have a 1.1.1 Unlocked/Jailbroken iPhone with T-Mobile and I just pay for the WAP (T-Zones I think they call it) for $5.99 a month. There is a hack found inside Installer (can't remember the Source. Google search "iPhone T-Mobile EDGE" or something like that and I am sure you will find it) that lets you use this service as EDGE. It works great for me so far. Not sure how much slower it is compared to "real" EDGE but everywhere I have looked online says that paying $15 more for the "real" EDGE service through T-Mobile isn't really worth it.

Hope I helped you out.:D
 
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