Communication device intended to link a user installation to an optical fibre, said device comprising: - a first connector intended to be connected to a first cable on which a first electrical signal occupying a first communication band is transmitted, a second connector intended to be connected to the optical fibre on which a second optical signal is transmitted, and a third connector intended to be connected to a second cable, said second cable being linked to the user installation, - a conversion module linked to said second connector, designed to perform a bidirectional conversion between the second optical signal and a third electrical signal occupying a second communication band separate from the first communication band, - a first transfer module designed to transfer the first signal between the first connector and the third connector in the first communication band, and to perform a bidirectional transfer of the third signal between the conversion module and the third connector in the second communication band, and - a power supply module designed to supply electric power from a supply voltage (POE, POE1) received on the third connector, said communication device being characterized in that: - the first cable and the second cable are coaxial cables; and - the supply voltage is received on the third connector in a third communication band separate from the first and second communication bands; and in that said communication device furthermore comprises a fourth connector intended to be connected to a telephone cable, and a second transfer module designed to perform a bidirectional transfer of the third signal between the conversion module and the fourth connector, the first transfer module then being configured so as to transfer only the first signal when the communication device is connected to the telephone cable. - a first connector intended to be connected to a first cable on which a first electrical signal occupying a first communication band is transmitted, a second connector intended to be connected to the optical fibre on which a second optical signal is transmitted, and a third connector intended to be connected to a second cable, said second cable being linked to the user installation, - a conversion module linked to said second connector, designed to perform a bidirectional conversion between the second optical signal and a third electrical signal occupying a second communication band separate from the first communication band, - a first transfer module designed to transfer the first signal between the first connector and the third connector in the first communication band, and to perform a bidirectional transfer of the third signal between the conversion module and the third connector in the second communication band, and - a power supply module designed to supply electric power from a supply voltage (POE, POE1) received on the third connector, - the first cable and the second cable are coaxial cables; and - the supply voltage is received on the third connector in a third communication band separate from the first and second communication bands; and in that said communication device furthermore comprises a fourth connector intended to be connected to a telephone cable, and a second transfer module designed to perform a bidirectional transfer of the third signal between the conversion module and the fourth connector, the first transfer module then being configured so as to transfer only the first signal when the communication device is connected to the telephone cable.