V.32bis
In the V.32bis method, which is used in modems for the long-distance telephone network, a total of 128 states are determined in phase by adding further phase angles compared to V.32.
6 data bits and one redundancy bit are transmitted at a step rate of 2,400 baud. V.32bis operates in duplex mode with transmission speeds of 9,600, 12,000 and 14,400 bps. It has Automatic Fallback( AFB) and switches the data rate to a lower data rate as transmission conditions deteriorate. V.32bis has error correction, V.42bis data compression, and Time Compressing Multiplexing( TCM), which uses up to 128 stages. ITU designations with the suffix "bis" are the second generation. This designation is an older German term for "second".