IPHONE 5 GAVE ME A NEW NUMBER

Hi everyone I ordered the iPhone 5 because my replacement iPhone 4 was corrupting and once I got it I tried to activate it and it gave me a brand new number. I ordered the Iphone 5 in hopes to keep my old plan which was unlimited.

I want my old number back but I don't know how to retrieve it. My wireless company that I use is Verizon. And my mother has verizon as well, but when I texted her it texted from my old number.

I called my old number and it went straight to voicemail because I shut it off.
But when I called the number that my iphone 5 gave me someone else picked up Help!
I'm CONFUSED I WANT MY OLD NUMBER BACK.

Call Verizon, they should be able to fix this for you.