From International Travel FAQs | Verizon Wireless
"TravelPass lets you use your domestic talk, text and data allowances while traveling outside the US in more than 100 countries for a low daily rate.
Instead of paying per minute, per message, or per MB you'll be charged a flat rate with TravelPass. The daily rate is $2/day in Mexico and Canada and $10/day in other countries where TravelPass is available. You'll use your minutes, messages and data allowances from your domestic plan. The daily charge only applies on days you use your service outside of the US, Puerto Rico and US Virgin Islands."
