There are only certain phones from certain providers that can be "flashed" to the Cricket network. (Thats what the rep. at the Cricket store told me anyway) I saw online that Verizon, Amp'd and Helio phones can be flashed over but don't quote me on that. It costs approx. $30 to have it done and from what I have heard all of your phones features may not work, i.e mms and web browsing capabilities. As far as doing it yourself.... can't help you there.
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so can the cricket store reprogram a phone so it would work on their service
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^ oh i didn't about this. i thought that once a phone is "programmed" from a certain service provider, it can't be reprogrammed anymore to fit other providers.
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I had the same problem, but I'm not sure how I have solved the problem.