How can I get my voicemail number back?

I have a Samsung A767 Propel, and I was trying to figure out how to change my voice mail to something personal (I could use some help with that, too) and I found it, and while reading the manual, I assumed I was supposed to change my voicemail number to my own, so...How can I get my voicemail number back?You would have to call AT%26amp;T to request it, because not all voicemail numbers have the same area code as your cell number.