A 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, said first and second node devices belonging to an electrical supply network using powerline and/or radio-frequency communications, the transmission method in so-called hyper-robust mode comprising: - transmitting (S210) said message, by said first device, to said second node device, on a first frequency band of a set of frequency bands comprising at least two frequency bands, said message being modulated according to a robust mode, a modulation according to said robust mode comprising successively a Reed-Solomon coding, a convolutional coding, a coding by code repetition and a BPSK modulation; and being characterised in that it further comprises: - transmitting (S220) said message, by said first device, to said second node device, on at least one second frequency band of said set of frequency bands, said message being modulated according to said robust mode and said first and second frequency bands being different; and further comprising the following steps performed by said second node device: - receiving said message on said first frequency band and on said second frequency band; - deducing therefrom that the first node device is configured according to the hyper-robust transmission mode; - changing its own transmission mode into hyper-robust mode in the case where its own transmission mode is different from said hyper-robust mode; - transmitting, to said first node device, an acknowledgement message on said first frequency band and an acknowledgement message on said second frequency band. - transmitting (S210) said message, by said first device, to said second node device, on a first frequency band of a set of frequency bands comprising at least two frequency bands, said message being modulated according to a robust mode, a modulation according to said robust mode comprising successively a Reed-Solomon coding, a convolutional coding, a coding by code repetition and a BPSK modulation; and being characterised in that it further comprises: - transmitting (S220) said message, by said first device, to said second node device, on at least one second frequency band of said set of frequency bands, said message being modulated according to said robust mode and said first and second frequency bands being different; - transmitting (S220) said message, by said first device, to said second node device, on at least one second frequency band of said set of frequency bands, said message being modulated according to said robust mode and said first and second frequency bands being different; and further comprising the following steps performed by said second node device: - receiving said message on said first frequency band and on said second frequency band; - deducing therefrom that the first node device is configured according to the hyper-robust transmission mode; - changing its own transmission mode into hyper-robust mode in the case where its own transmission mode is different from said hyper-robust mode; - transmitting, to said first node device, an acknowledgement message on said first frequency band and an acknowledgement message on said second frequency band. - receiving said message on said first frequency band and on said second frequency band; - deducing therefrom that the first node device is configured according to the hyper-robust transmission mode; - changing its own transmission mode into hyper-robust mode in the case where its own transmission mode is different from said hyper-robust mode; - transmitting, to said first node device, an acknowledgement message on said first frequency band and an acknowledgement message on said second frequency band. <EOS>