U.S. wireless roaming is free on all nationwide Verizon Wireless plans. While no additional fees are incurred during Verizon Wireless roaming, these roaming minutes are treated like your regular Verizon Wireless minutes.
For example, a U.S. roaming minute at 3 p.m. on Tuesday counts as a regular anytime minute whereas a roaming minute on Saturday would count as a free night-and-weekend minute.
International roaming minutes, on the other hand, are billed as separate minutes of use. These can be pricey with Verizon Wireless and range in price from 69 cents per minute all the way up to $2.89 per minute. These fees by country can be found here
Read more wireless roaming policies by carrier here