We have been VZW customers for about 10 years but wanted to save some money so we decided to try another carrier with the option of switching back if we were not satisfied. I talked to a VZW customer service rep, and was told that the billing would end as soon as the number was ported and if it was in the middle of a billing cycle, a pro-rated amount of the unused portion or when the phone was ported would be refunded in the following billing cycle.
This was apparently wrong information. You WILL get charged till the end of your billing cycle whether you can use your phone or not. In our case we ported our numbers over to another carrier, so our VZW phones were useless. This does not seem fair, but this is what I've been told. So basically since we cancelled our account on January 24th, but our billing cycle was from January 22 - February 21, we had to pay for basically the entire month of service from January 22 - February 21. This was a family plan of 4 numbers so this is basically an extra $224.49 of service that we had to pay for because "this was their policy...".
This may not be much money for a large company like VZW but it's a lot to a middle income family like ourselves. Oh well, live and learn I guess, but this has left us a little bitter, and a bit poorer for the time being. Just a heads up to anyone wanting to switch, make sure you time it right. 
