If I'm on the road, don't have a cellphone and a provider wants a telephone number, how useful is it to call her from my hotel?  Will the call classify as "unblocked"?

Seems that it would depend on the hotel whether the number would be identified or not. However, the best thing I can think of to do when leaving a message is to make certain that you give your full first and last name as well as room number. This way if dialing direct to the room is available; she will have your extension or room number, or if calling a front desk and/or hotel operator she will be prepared to ask for name of the person that registered to that specific room.

Then again, some ladies will just be too hesitant to return a call that is not a direct contact to you.

It is essential to hobbying.

Yes - what he said.  It's essential to hobbying.  And if you're worried about the bill coming to the house or something else like that, get a Tracfone or another "pay as you go" service.  That's actually the best thing I've found to help me in the hobby.  It's difficult to trace since you don't have a contract, can buy it with cash and don't have to have real contact information to activate it.

I agree with the guys above,  a pre paid cell phone will make life easier in this hobby.
Hotel or office numbers usually display as 'private number calling' and many escorts don't want to answer these calls as there are a lot of timewasters out there.

Hotels often track calls from the room and often show the phone numbers dialed on the bill. Even upscale hotels charge for calls from the room. The numbers being on the bill can be a problem when you file expense reports, or if self employed, have your SO find them.

sounds excellent - but does TracFone offer phones I can use in Canada?

Since you mention TracFone, a US cellular service, I guess that you are American.  In my experience, most prepaid cell providers in the US don't cover Canada, a lovely country I've visited, but never played in.  Still, my experience in both the US and UK suggests that you will be able to secure a local number, a phone, and enough minutes to secure to secure your desired encounter, or two, with 40-60 US$, I know this adds to your experience, but it is well spent!!!! A visit to a local electronics, or cell phone shop, should be you your stop when hobbying abroud, even in Canada.