Vessel Traffic Service (VTS) is basically introduced in ports and their approaches to monitor the compliance of a ship with the local regulations.
It also plays an important role in optimising traffic management. Vessel Traffic Service may be mandatory within the territorial seas of a coastal state.
On board a ship Vessel Traffic Service should form a part of the passage planning. Specific radio frequencies are to be given for the ship to monitor navigational or other warnings and seek advice on when to proceed to areas where traffic flow is regulated.
Vessel Traffic Service requirements are marked on the relevant charts. For more specific information sailing directions and list of radio signals should be used.