The maritime mobile service is a radiocommunications service which operates between: (i) coast stations and ship stations; (ii) ship stations; (iii) associated on-board communication stations. Stations on lifeboats and emergency position-indicating radiobeacons may also be included in this service.
The maritime mobile service provides an essential support ensuring the safety of vessels and crews at sea.
Due to the global nature of the maritime sector, the spectrum used is subject to international planning. The International Telecommunication Union https://www.itu.int/ (ITU), through the Radio Regulations, and the International Maritime Organization http://www.imo.org/en/Pages/Default.aspx (IMO) are the principal organisations involved in the harmonised definition of the various frequency bands and modes of maritime service operation.