18. A text compression unit for disposition between a local text encoding and decoding station of a telecommunication network and the communications network interface for communication with remote stations which may or may not be equipped with a similar text compression unit comprising: multiplex means for coupling the unit between the local text encoding and decoding station and the network interface unit, and data processing and storage means coupled to the multiplex means for automatically receiving a standard data stream from the local station, compressing the standard data stream to produce a compressed data stream, and sending the compressed data stream to a remote station, and for receiving a compressed data stream from a remote station, decompressing the compressed data stream received from the remote station, and sending the decompressed data stream to the local station and for compiling a library of data units in a memory during compression of the data by writing each data unit into the memory upon the first occurrence of each data unit and for each occurrence thereafter compiling the address of the data 1 unit in the library instead of an original representation of the data unit.
18. A text compression unit for disposition between a local text encoding and decoding station of a telecommunication network and the communications network interface for communication with remote stations which may or may not be equipped with a similar text compression unit comprising: multiplex means for coupling the unit between the local text encoding and decoding station and the network interface unit, and data processing and storage means coupled to the multiplex means for automatically receiving a standard data stream from the local station, compressing the standard data stream to produce a compressed data stream, and sending the compressed data stream to a remote station, and for receiving a compressed data stream from a remote station, decompressing the compressed data stream received from the remote station, and sending the decompressed data stream to the local station and for compiling a library of data units in a memory during compression of the data by writing each data unit into the memory upon the first occurrence of each data unit and for each occurrence thereafter compiling the address of the data 1 unit in the library instead of an original representation of the data unit. 22. The text compression unit of claim 18 wherein the data processing and storage means further includes a fixed library of words each stored at predetermined addresses from which the words can be read, a variable length encoder for encoding individual text characters as a variable number of binary bits with the least number of binary bits used to represent the most frequently occurring characters, and wherein the data processing and storage means compiles a compressed message by, with respect to each successive word of the standard message, (a) searching a fixed library for the word and compiling a first escape code plus the address of the word in the fixed library if the word is found, and if the word is not found (b) searching the reconfiguration library for the word and compiling a second escape code plus the address of the word in the fixed library is the word is found, and if the word is not found, then (c) writing the word into a word position of the reconfiguration library selected in a predetermined manner and (d) encoding each character of the word in a variable length code, and wherein the data processing and storage means compiles a decompressed message from a received compressed message by (a) unless a second or first escape code is detected, decoding the variable length code to compile the words in standard form in a standard message and writing the decoded characters of the words into a word position of the reconfiguration library selected in a predetermined manner, and (b) if a second escape code is detected, compiling the word from the address of the reconfiguration library received with the second escape code, and (c) if a first escape code is detected, compiling the word from the address of the fixed library received with the first escape code.