How to activate facetime on verion iphone4?

i got my two iphone 4's yesterday from verizon-wireless. I activated them using itunes like it said to. I went to settings, then phone, thenit said facetime activation unsuccessful. I switched it off and and turned it back on (facetime not the phone) and it said waiting for activation. how do I activate facetime? I have verizon-wireless iphone 4 16gb 4.2.5

Check this out:

http://artoftheiphone.com/2010/06/24/basics-how-to-activate-facetime-on-the-iphone/