I've just started experience similar text message failures in the past few days. The error states "message not sent" but, if fact, the messages are going out. The error surfaces immediately upon sending. I've been to the Verizon shop without success. I was left with the suggestion to do a factory reset. However, based upon several threads, it was unclear that a reset would correct the issue. I'd like to avoid a factory reset. Any recommendations?
I have the S3, after reading a lot, I removed the battery and SIM card for a minute. Reinstalled and SMS pictures are sending immediately. Not real happy about this solution, but it worked on not only my phone but my wife's S3 as well