I am going to Arizona with my job for a year from Ireland. Will I be able to use my Euro HTC Wildfire in the US? With what carrier? I need an answer as detailed as possible.
I think you can't. see availability:
Wildfire : http://en.wikipedia.org/wiki/HTC_Wildfire
if you buy Sim card i believe you will be able to use it. HTC Wildfire supports US networks i think that do not support Asia frequencies.
only if your phone is not locked to your mobile operator. If that;s the case the phone will only
work in Europe unless you purchase the unlock code from the operator or unlcok it yourself
(not recommended if you're not sure what needs to be done)