I'm currently trying to get an unlocked HTC One M8 phone to use on my current Metro plan. Am I able to buy any unlocked HTC carriers like Verizon, ATT, Tmobile, Sprint, and factory unlocked ones or am I able to only use certain carriers like Tmobile and ATT? Once I do have my unlocked phone and my Metro SIM card, can I activate the phone myself or do I have to go to a store to do it? Also, do I automatically keep my current number I have once I switch to the HTC? Thanks.