Typically, an 800 number is translated within the PSTN to a local 7 digit number. Your system should never see the 800 number, only the local 7 (or 10) digit number.
That being said, some carriers offer a service, which displays the 800 number being dialed on the incoming service (you may lose callerID name or number with this feature turned on). This allows people to know to keep conversations short since they're paying for it.
This service is not available on digital PRI services however. Not in Canada, anyways.
So the short answer is, no, you should not have to do anything different to get a toll free number to work, as long as it points to the same main number you have working. But you have to talk to your carrier to make sure and to see what options you have.
