Noah's sister is going to France in May and wants to know the best way to travel and still use her phone. Leo says that Noah's sister uses Verizon, which is the worst for traveling. T-Mobile and Sprint are the best because they have free, albeit slow data through One World. Leo says that the best option may be to just buy a local SIM card and then swap out her SIM while she's in France. She can also local Wi-Fi, which won't cost anything. She can also rent a MiFi device which will give her an LTE Hotspot which she can add her phone to, as well as her laptop or tablet. She can also cache her maps while she's on Wi-Fi and use them without cellular service. She can check out prepaidwithdata.wikia.com
She should make sure she turns off International Data Roaming, though. If she forgets this step it could cost her thousands!