Stats barred means the government can't take any legal action against you to recover money owing except those involving the right of offset, such as witholding your GST and income tax refunds. However, they can hire a collection agent to nag and scream bloody murder at you about it forever. Ask Mark Silverthorn, if you don't belive me.
Your loan was originally divided into at least a federal and a provincial portion. The collection of those 2 may have been further subdivided since then but, irregardless, those 2 Acts will ultimately govern what collection efforts will be allowed.
The federal student loan program has been replaced by the Canada Financial Student Assistance Act, which has been updated in 2000 and 2001 by Bill C28, Part 3. You should read all of Sections 16.1 and 16.2 so as to know what applies to your individual loan.
http://laws.justice.gc.ca/en/ShowFullDoc/cs/S-22.7///en
The Federal Portion has a Limitation of Actions of 6 years, subject to revivals and renewals via signed written acknowledgements. Also, as you surmized, as per Sections 16.1(6) and 16.2 (8) of the Act, the running of the limitation period may be suspended by interest relief periods.
The wording is that a suspension occurs during any period which no legal action may be commenced. That would seeem to indicate an interest relief period. (I was unable to find any rulings on to confirm that though, and so you should check it out with someone qualified in that area.)
That's important because, due to the age of your loan and the fact that you had interest relief periods for up to 30 months, your case may be on the verge of being stats barred. That may be why you are now getting those collection calls. Collectors often do that as a loan nears its stats barred date as a last gasp attempt at recovery. Or, at least, they try to trick you into providing a written acknowledgment of the loan to renew the limitation period.
Similarly, Section 14 of the Student Financial Assisitance Act of 2002 of Alberta gives a 6 year limitation period for the start of legal action for student loans. Notably, no mention is made of any provision for the suspension of the running of a limitation period by interest relief periods.
http://www.canlii.org/ab/laws/sta/s-20.5/20030217/whole.html