Ship movement service (short: SMS; also: ship movement radiocommunication service) is â according to Article 1.31 of the International Telecommunication Union's (ITU) Radio Regulations (RR) â defined as ëA safety service in the maritime mobile service other than a port operations service, between coast stations and ship stations, or between ship stations, in which messages are restricted to those relating to the movement of ships. Messages which are of a public correspondence nature shall be excluded from this service.û
The ITU Radio Regulations classifies this radiocommunication service as follows:<br /> Mobile-satellite service (article 1.25)