ITU Radio Regulations

Call Sign Usage

  • Amateur stations are required to transmit their call sign at short intervals during the course of their transmissions
  • Call signs must be suffixed with /M when operating land based mobile and with /MM when operating maritime mobile
  • When operating /M or /MM the location or position of the station must be sent at the beginning and end of a contact with each station or at intervals of 30 minutes whichever is the more frequent