check your airtime bro, either that or or your contract was cut for some reason..or wait maybe you dont have a sim in your phone or you are trying to use MTN in a place with dog reception aka America..
In my phone settings I go into the SMS settings, there a whole lot of message centers defined. I delete them all, turn the phone off and on again and it registers a new message center... except...... it's the Vodacom number (+27829119) and I'm with MTN which shoudl be +27831000002.
Why would i t try to send messages through the Vodacom message centre instead of the MTN one?
OK, working again. Turns out it's Vodacom's fault (bunch of idiots!!)
Turns out, when you use your MTN SIM card in your friends laptop with the Vodacom Mobile software, it overwrites the message center number stored on the sim card with the Vodacom number!! (IDIOTS!!!!)