Yes you can. However, 4G smartphones cannot be activated on prepaid. 3G devices have 3 different available plans. Verizon has an exclusive plan with Walmart which consists of unlimited talk and text with a 1GB for $50. The other 2 plans are unlimited talk and text with 2GB for $60 or 4GB for $70
And to add to that, since you posted under the iPhone 4 device section, you would be able to use it since that device is not 4G capable.
what i mean to reiterate is if can still stay using the $1.99 scheme on pay as you go plan, if i'm not feel like using or registering on $60 and $70 scheme on smartphone prepaid plan to maximized my money... thanks!