So, whether it be on here or craigslist or ebay, how do i/can i assure that the phone is good and doesn't have a bad ESN? i'd hate to meet up with someone, give them cash, only to find out the phone is a dud. could i call a phone carrier and give them a serial number or something of the phone and they can check if its good or something? For those sellers out there, I'm in the market for a used G2X or a used Galaxy S 4G for TMobile for my girlfriend at a decent price. Thanks in advance!!