This is a copy of the Verizon chat I just had moments ago.
" Thank you for contacting the Verizon Wireless Chat Team regarding traveling abroad. How can we help you today?
You
Both our phones are on the 2GB plan. We will be in Canada both going and coming back from Alaska. If we add TravelPass at $2 per day on days when our phones are used, will we have any other charges such as any roaming charges????
Verizon
Hello! I would be happy to help with this today and go over opitons! While I open your account, May I have your first and last name?
You
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Verizon
Thank you Dianna. If you were to enroll in TravelPass for your trip it will be $2 per line/ per day and there would be no other charges involved. You would also both have access to your normal domestic plan!
You
OK--Thank you. We will sign up just before we leave in May. Thanks
Verizon
You are more than welcome! Did you have any other questions for me today?
You
No
Verizon
Thank you for chatting in and being a valued Verizon customer! It has been a pleasure speaking with you. Whenever you are ready you can click the "X" in the corner to end the conversation. Have a wonderful rest of the week! :)"
So, according to Verizon our regular 2GB plan allows us use of our existing US plan with no roaming or other charges other than the TravelPass $2 per day only on days when phone is actually used. We will put just one of our phones on the plan just before we leave home in mid May.