Therefore, error-correction is necessary. All modems in a network must be using the same error-correction protocols for it to work. Fortunately, most modems use the same protocol, V.42 . With it, modems can detect damaged data streams, and the data will be resent. The V.42bis protocol is just like V.42, but it incorporates data compression.
Data compression allows modems to use higher bps's.
A 14.4 modem with data compression, can boast transmission rates of 57,600 bps. A 28.8 modem will boast transmissions of 115,200 bps.