SOL is 2 years for Ontario from date of last activity (payment or acknowledgment of debt - in writing).
Do not acknowledge the debt on the phone or in writing. Do not entertain their calls if the SOL is over. If the date of last activity on the account was late 2008, you are still within the SOL and therefore the threat of filing suit is real, so demand validation, challenge the debt and suggest they take it to court, send a cease and desist letter from contacting you in any way except via Canada Post, and then come back here when you've heard back from them.