This is not a random hacking issue. My boyfriend recently transferred his phone number from his family's Sprint account to my Verizon one. It's been about a month and his new phone works with his number like usual. Yesterday, his mother sent a group message to the family and it showed as coming from my boyfriend's number, even on his phone which did not send the text. Can this possibly be a fluke where the number is active on both Sprint and Verizon, or does it have to be some kind of spoofing situation?