A message-transmission method for transmitting a message from a first node device to a second node device belonging to a network neighbourhood of said first node device is described. The first and second node devices belong to an electrical supply network using powerline and/or radio-frequency communications. The first node device transmits said message to said second node device on a first frequency band and at least one second frequency band of a set of frequency bands comprising at least two frequency bands. The message being on each occasion modulated according to a robust mode, a modulation according to said robust mode comprising successively a Reed-Solomon coding, a convolutional coding, a code repetition coding and a BPSK modulation.