ok... so if you were to go to the states for example... you are on t-mobiles network... now you make a call on edge, you pay the roaming fee pulus long distances... BUT if you have talkspot/UMA, and you connect to wifi and call on the UMA... the carrier (rogers) has NO idea where in the world you are... so if you would be either billed local minutes as if you were calling from your calling area(if you dont have the talkspot option) or if you have the option then its all unlimited...
why dont you head to the rogers website and read up on the talkspot option...
heres a link for you:
Rogers Communications - Wireless, Digital Cable TV, Hi-Speed Internet, Home Phone