I had a friend who worked for an ISP in Montreal, and he showed me the map of coverage of the island, colour-coded by which exchange served that area. There we

I had a friend who worked for an ISP in Montreal, and he showed me the map of coverage of the island, colour-coded by which exchange served that area. There were a lot of rectangles and squares, but there were also some weird shapes, strange cutouts, or long stretches. I think there were even some islands of coverage A surrounded by coverage B. You can be fifteen feet from the CO, but that doesn't mean that's the one they ran your lines from.