U.S. wireless roaming is free on all nationwide Sprint plans. While no additional fees are incurred during Sprint roaming, these minutes are treated like your regular Sprint minutes.
For example, a U.S. roaming minute at 3 p.m. on Tuesday would count 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 minutes do not pull from your regular monthly plan minutes. It can take 30 to 60 days before international roaming usage appears on your Sprint invoice.
International roaming can cost up to a pricey $4.99 per minute with Sprint. Sprint lists its international roaming rates here. Read more wireless roaming policies by carrier here.