Here the modems improve on class 4 by compressing the data. The compression achieved
will run from about 1.3:1 to 2:1. PKZIPped files will not compress at all. The
protocol efficiency will average about 200%. A 2400 BPS (Bits Per Second)
modem will realise a throughput of about 4800 BPS.
MNP-5 is not part