I agree with the above posters saying you have 30 days, and your contract will revert back. I was told the same thing by about 3 or 4 different CS Reps.
One of the few things that I am consistently happy with re: Verizon is their Customer Service. I've explained on numerous phone calls (when I was debating on getting a droid) that I was thinking of changing providers (to an I-phone) and that I needed my questions answered. Then I called again with the devour came out. I got an ADDITIONAL $50.00 credit for when I renew my contract, and they always took their time, and verified I had all my questions answered before I got off the phone. They also basically told me how to "work their own system" how I could use the upgrades on my Family plan, if I wanted to get another Verizon phone this summer. Also they offered my New every two discount credit early, (2 months) which I was shocked by. Now granted, I was very direct in explaining I was perfectly fine with going to ATT to get a more desirable phone, so they seemed actually "worried" they might lose me.
I WILL SAY. That the manager of my verizon store here, would not honor my credit given to me, nor would they let me use the "early" New every two credit. I could only do that over the phone, and honestly I was really put off how the IN STORE manager treated me. But their Customer Service over the phone is phenomenal, IMO.