ATT Messages not sending!?

So today I recieved a message from my friend asking me a question, I wrote back twice, but the next morning I recieved another message, asking me why I didnt answer.. The exact same thing has happened to me before, and at times when they would recieve a message a day later, it has happened on the phone I owned before this one as well so it cant be the phone.. Whats wrong with this, do I have some settings set up incorrectly or something? I do get a "Message Sent" window when I send it which makes it even worse if im actually charged for it. I use a samsung d900i quadband btw.

---

› See More: ATT Messages not sending!?

Maybe the person you're sending the message to is having an issue? Try with someone else?

From AT&T to what Provider though?

Yeah, is it to only that person or is it to other recipients?