Paul, they do not work in Canada, with near Nil customer service, you think they will work in US or any other part of the world...... My two cents worth DO NOT GO for FIDO if you can help it.

will there be a cost to unlock my cell so I can use it in the USA when I travel

Hey Paul. Once your Fido phone is unlocked, you can use it in the US with AT&T or T-Mobile.

Hi there. Yes, it will work with carriers that support GSM.