There is no frozen ATPL in Canada.
The normal progression is to complete a CPL, MULTI IFR. If you are going to fly in a 2 crew airplane, you'll also need to complete an exam called the IATRA exam. This exam is basically the ATPL exams trimmed down a little.
Or once you have 750 hours you may write the 2 ATPL exams. When you obtain the ATPL flying requirements from the CARS, you can apply and receive the ATPL.
Another way is to complete the Integrated ATPL course which allows you to write the ATPL exams with 200 hours instead of 750 hours. You still don't get a ATPL until you have the flying requirements from the CARs.
In Canada the majority of pilots get their start in general aviation, almost none get their start in a Transport Category aircraft. It is the blessing and curse of the Canadian system of aviation.
Adam