How to turn off a number on my iphone?

Me and my brother were on a contract with Sprint and then we switched to AT&T. Along with the switch the company also switched our numbers. So in order for me to get all my old apps and stuff on my phone i had to back up my new iphone to the old one through icloud. Now whenever I send a message to my brother, I'm basically sending a message to myself.

Well are you sending it through iMessage? If you keep having this problem, go to at&t or the Apple store and they should fix the issue for you. I know that wasn't much help, But you didn't give enough information about the problem.

Hope this helped though! =D