HTC Droid DNA - I have had unsuccessful SMS delivery - Cause Code 65535 Error Code 3 - off and on for the past 2 months. Phone numbers are in correct format (no "1" preceding the number) and I have restarted my phone countless times (even switching from wifi to mobile data). This is happening no matter where I am - home, traveling ,etc and it is very frustrating. I do know that some of the individuals use iPhones (diff carriers) but not all. Any advice because I am at my wits end.