Phone contract HELP!!!?

I have a new phone that I just upgraded to from Sprint. I did this upgrade on June 5, 2011, when getting the phone I know you get a 2 year contract on it and if you want to get rid of the phone you have to pay a 200.00 termination fee. When reading the booklet that comes with the Nexus S it says that you can call Sprint in my case within 30 days after the effective date of the change and specifically advise us that you wish to cancel Services because of a material change to the Agreement that we have made. Then it says if you don't cancel within 30 days you get charged with an early termination fee after the 30 day period. I want to switch to Verizon to get the IPhone 4 and I need to know if it is okay to cancel the agreement!!!