 The FidoNet system was based on several small interacting programs, only one of which needed to be ported to support other BBS software.FidoNet was one of the few networks that was supported by almost all BBS software, as well as a number of non-BBS online services.This modular construction also allowed FidoNet to easily upgrade to new data compression systems, which was important in an era using modem-based communications over telephone links with high long-distance calling charges.