Abstract: A telecommunication system has a space segment which includes a satellite carrying a multibeam telecommunications payload and a terrestrial segment comprising gateways for access to a terrestrial network. There is one gateway within a terrestrial coverage of each beam or of a group of beams. User terminals communicate with the payload of the satellite. The payload has, on a forward path from any gateway to any user terminal, a frame by frame routing unit for messages transmitted in time division multiplex. On a return path from a user terminal to a gateway the payload has a routing unit operating within each group of carriers belonging to a given beam.