Several protocols have been developed over the years to deal with transmission errors. LAP-M are the newest and best of these error correction protocols, but most modems support the older MNP versions as well. In addition to raising the basic bit per second rate of connections between modems the processing power of newer modems can also support data compression protocols. These protocols enhance end to end throughput by replacing repeating sequences of user data with a shorter encoded form prior to sending it to the remote modem. See Getting the Most Out of Your Modem for more detail.
Data compression is most effective when text files are being transferred.
Some modems actually slow down when they are trying to compress such files, and their vendors often suggest disabling data compression in this context. Data compression protocols cannot be used unless error correction protocols are also being used. Data compression protocols are used for performance only. They have nothing to do with data integrity or reliability. None of the software packages and drivers supported by KU include RPI, and neither do the common WWW browsers.