Recycling of telephone numbers | Technical service details | Consumer forum

Anyone know how long a previously used telephone # has to remain inactive before it is assigned to someone else by one of the telephone companies?

Recently activated a new SO phone bought in Toronto, late August, and was surprisingly assigned a 416 area code #, rather than one with the new 647 area code. Within a few days a couple of text messages were received presumably intended for prior holder of #, although I guess they could simply have been misdialed (twice!) calls.