According to
this article,
"Like AT&T did initially with its policy, Verizon also targets the top 5 percent of the heaviest data users. But the company uses network intelligence to only slow down those heavy data users when the network is actually congested.
The way it works is that if you use more than 2GB of data per month, Verizon is likely to identify you as being in the top 5 percent of data users. Once you've been identified as a heavy data user, when the cell site you are in gets congested, Verizon will slow down your access until the network is no longer so crowded.
Once the congestion has subsided or you move to a different cell site that isn't congested, your speed returns to normal. Depending on how congested the network is your service could be slowed for a few minutes or for several hours.
The policy only applies to customers with unlimited data plans on the 3G network. Verizon doesn't slow down data for 4G customers."
