27. In addition to allowing internal communications between all the users of the system, the communication system installed by the operator must be designed to at least allow(1) the identification or location of persons who access the communication system;
(2) a complete coverage of tunnels, tracks and stations of the REM;
(3) bidirectional communication with the control centre, including for REM users;
(4) the possibility to communicate safety information to users; and
(5) the recording of the information.