Open question: Can a debt collecting agency go as far back?

My husband was asked recently over an old debt (10 years old - year 2000). I read the statue of the restrictions for Ontario and suggest it that everything is held 2004 ago to the 6-Jahr-Richtlinie, which naturally past is. My husband also at all does not remember to reach this debt at all. How would you treat to us the debt collecting agency and the expenditure would suggest, which are to the hand?