Telebit TrailBlazer
The pricey high-speed modem that, in the late 1980s, carried a large share of Usenet's traffic over ordinary phone lines.
While regular modems struggled along at 1200 and 2400 bit/s, the TrailBlazer used Telebit's proprietary PEP (Packetized Ensemble Protocol), which split the line into a large number of narrow carriers and tuned each one to the noise on its frequency. On a good line that meant around 18,000 bit/s — at a time when no standard came anywhere close.
The clincher was that the modem spoke UUCP itself. It acknowledged packets locally rather than waiting for the far end, and the latency that otherwise strangled transfers disappeared. Telebit sold the units cheaply to Usenet sites, and for a few years the TrailBlazer was the invisible engine behind the news feed. V.32bis and later V.34 turned it into a curiosity.