Abstract: A network device has a processor to control message traffic between the network device and other devices in a network, a port to allow the network device to send and receive the message traffic and a transcompression element to receive indicators of compression renegotiation messages and to transmit indicators of compression renegotiation acknowledgement, as well as perform compression/decompression. A method of controlling compression in a network receives an indicator of compression renegotiation at a decompressor on a first network device, and transmits an indicator of compression renegotiation acknowledgement to a compressor element on a second network device. Another method of controlling compression in a network determines if a compression method for outgoing data is compatible with a decompression method for incoming data.

Abstract: Disclosed is a data compressing modem for connection to a decompressing modem over communication lines. The compressing modem receives an input data stream, and each character in the data stream is recodified with a compressed character code, the length of which is dependent on the frequency of the character in the data stream. A frequency table is maintained so that changes in the relative frequency of characters in the data stream will be recognized by the compressing modem and the compressed character codes representing such characters will be exchanged accordingly. A decompressing modem, which is connected over communication lines to the compressing modem, processes the compressed character code in a reverse order from the manner in which the compresing modem processing the codes. The decompressing modem also maintains a relative frequency table and as the relative frequencies of the various characters change, the actual characters represented by the compression codes must also change.

Abstract: Disclosed is a data compressing modem for connection to a decompressing modem over communication lines. The compressing modem receives an input data stream, and each character in the data stream is recodified with a compressed character code, the length of which is dependent on the frequency of the character in the data stream. A frequency table is maintained so that changes in the relative frequency of characters in the data stream will be recognized by the compressing modem and the compressed character codes representing such characters will be exchanged accordingly. A decompressing modem, which is connected over communication lines to the compressing modem, processes the compressed character code in a reverse order from the manner in which the compressing modem processing the codes. The decompressing modem also maintains a relative frequency table and as the relative frequencies of the various characters change, the actual characters represented by the compression codes must also change.

Abstract: Disclosed is a data telecommunications system and method in which at least one modem which, capable of operating at a variety of transmission speeds, selects the proper speed at which to operate. An initiating modem capable of operating at a plurality of operating speeds compares the maximum operating speed of a receiving modem, and if a match is found, operation begins at that operating speed. If no match is found, operation begins at a default transmission speed.