My phone number is not deleting off of my iphone when I go to wipe it out, what do I do?

I have sprint, and I'm trying to sell my phone on ebay. I don't want anyone having my personal information, so I tried wiping everything out several times and it still is showing up with my phone number and the SIM card isn't even in there! What do I do?

I have sold my iPhone 4 on ebay last week. Yes, it is wise to permanently wipe everything on your iPhone. Use this software, it offers you the safest and most effective way to protect your personal data by using US Military spec over-writing technology to erased all content and settings on iOS devices. Afterwards, there will be no recovery software can work.
Download from: http://www.safe-eraser.com/

Go to a locking/wiping service. (Google it, in the area I live in they have one in the mall.) Pay the twenty dollars, and they will take care of it for you, but make sure you tell them to do stage 1, because stage 2 will destroy the phone. They use effective brute-force methods that work.