Abstract: In a digital telecommunications network having first and second addressing zones, a name and address server in the first addressing zone receiving from a first address of the first zone, assigned to a source machine, a request to provide an address in relation to the name of a destination machine situated in the second addressing zone, sends to a second address of the first zone a first packet containing at least the said name of destination machine, said second address of the first zone being associated in a static manner to a first address of the second zone, assigned to a management unit. The management unit sends to an interface a second packet destined for the name and address server comprising as origin address, a second address of the second zone assigned to the destination machine.

Abstract: An interface between a data terminal and a digital communications link implements protocols and frame formats designed to reduce delays in a data communication with a remote terminal. The interface overcomes the need to send or receive an HDLC SABME or UA control signal, and allows data to be sent over the digital communications link as soon as the communication parameters are established. In a non-ARQ (error correction) mode, the interface sends control signals and data over the communications link in frames subdivided into many small subframes of fixed length, each subframe having a length code. The interface, when arranged for connection to the data terminal through a telephone network, encodes call progress signals from the telephone network for sending over the digital communications link. The interface encodes and decodes interrupt signals for sending between the data terminal and the digital communications link when an interrupt signal is detected.

Abstract: An interface between a data terminal and a digital communications link implements protocols and frame formats designed to reduce delays in a data communication with a remote terminal. The interface overcomes the need to send or receive an HDLC SABME or UA control signal for establishing an asynchronous balanced mode, and allows data to be sent over the digital communications link as soon as the communication parameters are established. In a non-ARQ (error correction) mode, the interface sends control signals and data over the communications link in frames subdivided into many small subframes of fixed length, each subframe having a length code indicating an amount of valid information but without CRC, address or control information. The interface, when arranged for connection to the data terminal through a telephone network, encodes call progress signals from the telephone network for sending over the digital communications link.

Abstract: A communications link for data communication via satellite includes interface apparatus comprising a satellite link interface for connection to a satellite link and a PSTN interface for connection to a PSTN. The interface apparatus supports different data compression modes in the communication link. Mode A allows data compression over the PSTN but not over the satellite link. Mode B allows data compression over the PSTN and over the satellite link, but enables decompression and recompression of data flowing in each direction through the interface apparatus. Mode C allows compressed data to pass transparently between the PSTN and the satellite link, while the interface apparatus performs error correction on the satellite link and on the PSTN.