Mobile telephony on-board a vehicle

Data messages originally formatted for transmission over the cellular telecommunications network for generation of a display on a display unit of a cellular telephone, can instead be transmitted over the satellite network for display on the information and entertainment system of an aircraft by replacing the address information in the original data message by address information appropriate to the selected display unit to generate an amended data message. A new data message is created, addressed to the server of the information display system and having the amended data message as payload. The onboard server means for converting the amended data message into control instructions suitable to display the information content of the data message on the information display unit identified in the amended data message.