I am sure this question has been asked before but I haven't found any threads yet that have fully answered my question. I have the opportunity to get a Sprint phone for a good deal. The only problem is that I am on at&t at the moment. I understand that Sprint is cdma and at&t is gsm. Can I sim unlock the phone to get it working on at&t? If I can get it to work, will I lose functionality such as LTE?