Call in points on charts are used by large vessels travelling in shipping lanes or along Shipping routes. See Rule 10 of the Collision Regulations for the rules for shipping lanes. The Canadian Collision Regulations can be downloaded for free. The best source is the laws-justice website. As kayakers we should stay away from shipping lanes. As per Rule 10, if we are crossing them, we must do so at right angles to the shipping lane so as to get across and out as quickly as possible. As a kayaker, if I were planning to cross a shipping lane, I would first make a call to Vessel Traffic Services on the appropriate channel to determine the traffic and to let them know of my intentions so that they can warn vessels in the area.
The call-in points are used by Vessel Traffic Services (operated by the Coast Guard) to monitor the movement of ships. It is compulsory for some vessels and voluntary for others to call in at each CIP. What this means for us as kayakers is that we can, if we like, monitor the appropriate channel to determine which ships are in the area based on their calls at the various call in points.
The channel differs depending on the area you’re in. From what I’ve seen, the only channel that remains constant across all locations is channel 16. The Canadian version of the publication “Radio AIDS to Marine Navigation” will tell you which channels to use for a particular area. It is available in Marine stores or downloadable for free from the Canadian Coast Guard.