The invention concerns a communication system via ACARS messages intended to be placed onboard an aircraft, said system comprising a router (310, 310′) adapted to route said messages from and to a plurality of VHF, HF, SATCOM sub-networks. The system comprises a switch (360, 365) and an AoIP conversion gateway (380), the switch being connected to an HF or SATCOM transceiver module (340, 350) by means of a first two-way link (341, 351), and to said AoIP gateway by means of a second two-way link (381), the switch being adapted to select said first two-way link when it lies in a first switch position and the second two-way link when it lies in a second switch position, the switch lying in the second switch position if the aircraft is on the ground or less than a predetermined distance from the ground, otherwise it lies in the first position.