If you put your SIM from the older GS3 into the new GS3 can you send and receive texts with the newer GS3? And vice versa does the older GS3 not send and receive with your father-in-law's SIM? If so the fault may lie with Verizon, his account is not set up properly, or the SIM. By chance did your FIL have an iPhone before and use iMessage? If so he'll have to logon and turn off iMessage.