Roaming plan options: https://www.verizonwireless.com/solutions-and-services/international-travel/
Roaming plans must be added to each line that will be used out of the United States. Please note no plan covers airlines use airplane mode. Plans for land travel do not cover cruise ships.
Easiest is the $10 TravelPass per day. Make sure you have TravelPass on your account, you only get charged days you use it. And make sure you have your phone set to allow Roaming.