Like the author, I also rolled my own SMS-over-XMPP solution a few years ago. One central ongoing frustration is that a lot of what people think is SMS really ends up being MMS. Not only do I miss pictures, but people send group texts that silently miss me, and messages over the SMS character limit are also sent over MMS. It sends 160 characters over SMS, and the rest is chopped off if you don't have MMS. Some (many/most?) messaging apps don't give you a character count any more, so I can't even tell people to watch the characters...

I believe Twilio has some sort of MMS support, so maybe this could be made to work with their service. My VoIP provider doesn't support MMS, so I may have to migrate to Twilio some day.