If you don't get service (signal) anywhere, you can't use the iPhone at all in any way.
If you meant something else, I think I can help:
Yes, you would talk to them about your iPhone.
Now, the proceedure is fairly technical, so if you don't feel that all of the people you know call you "That phone geek with the unlocked iPhone" behind your back, you might want to turn back now. :-)
First:
You don't need an unlocked iPhone. You need an unlocked iPhone that is also "jailbroken." If you don't know what that means, you are in for a rough ride on this project. Jailbreaking an iPhone involves changing the software/firmware of the phone so that you can run completely unauthorized apps and new versions of the iPhone software that Apple does not want you running on your phone.
So if your iPhone has made the jail break train, and escaped from the land of things that all belong to Apple, then you are good to go.
Now the reading list: First, read this:
How to get T-Mobile Edge to work on an unlocked iPhone:
"T Mobile Edge Settings Available Now - 100 % Working:"
When you are all done reading you should have complete instructions to get your iPhone configured to use Edge.
If you have any further questions, please leave me a very detailed message with any error messages you get after having tried EVERYTHING to get T-mobile's Edge working on your Apple iPhone.
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