Sony Xperia Play CDMA to GSM
Not going to happen. Sorry. While MSM8655 supports GSM - Play Verizon's version of radio software makes no use of it. You can not reflash the radio software because the bootloader is locked. And even if you could - the GSM bands are not "phased" in your phone. "Phasing" is a process of calibrating the phone during manufacturing - without it you would get no 3G, at best you could probably get very poor 2G performance if any at all.