Hello KellyH,
Welcome to the community!
Firstly to clarify, do you have a pre-paid or post-paid plan?
It would be important to note that the US has shut-down their '3G' networks (see here). As such, Fido no longer offers pre-paid roaming in the US (see here).
If you chose to switch to a post-paid plan, you should note that you would need to migration your services over. in doing so, a credit check would likely be required (see here). The migration can only be done by contacting customer service to have them switch your plan types (see here). In addition, they can also be contacted via Live Chat, Facebook, or Twitter. Those methods can be accessed via the contact page posted above.
You should note there would be a migration fee required which would be applied to your next post-paid bill. You should note that if you chose to switch back to pre-paid after that period of time, you would likely incur an additional migration fee.
As already mentioned, you would have access to Fido Roam with a post-paid plan (except Basic Plans). You would need to ensure your phone and plan are capable of voLTE (and roaming voLTE) if you did wish to make use of calling.
Hope this helps 😀
Cheers
