Urgent Help!

Since i’ve got my iPhone back from repair.. it’s stopped sending SMS.. Whenever i send a SMS it gives me a “error sending message ” thingy.. Now i can send and receive calls.. and can receive SMS too.. but i cant seem to send any.. Can anyone help me out with this.. Thanks In Advance!
Answer #1
This may be the answer..The message centre number may have been erased..
yeaaaaaaaaaaaaaaaaaaaa
after hours of research i found a solution for this sms problem
its the sms message center number u need to put n iphone so u could send sms to everyone
wat u need to do is this on iphone type this
*5005*7672*XXXXXXXX# Call were xxxxxxxx is message center number provided by carrier to get this number u need to call customer service of ur carrier
http://forums.macrumors.com/showthread.php?t=374641
Answer #2
Have you verified the message centre number of your carrier. It might have been altered.
Answer #3
Is it the same way with every carrier?? i mean *5005*7672*XXXXXXXX# where XXXXXXXX is da message center no..?? So it gets ok just by calling that number??