In the case of a bank, whose host runs ATM and teller applications over separate lines, a multiport/multipoint modem may be used to combine the applications over a single multidrop line
for cost savings of 25-60% on voice-grade private lines.
That's because frame relay eliminates the shared multidrop lines
and associated polling that occurs over the wide area network.
They replaced the analog multidrop lines
with individual digital leased lines from the Tampa headquarters data center to each branch location.
A low-speed hierarchical data network based on interconnected multidrop lines
provided the communication between the dumb terminals and the hosts.
But in the case of IBM's 3270 Bisync, a positive-acknowledgement protocol, these delays can be overwhelming to the point of rendering multidrop lines
In development for five years, and still growing, Ventura County's data processing system today includes two IBM mainframes, nine Hewlett-Packard minicomputers and 800 terminals and printers, including some on "local" multidrop lines
as far as 40 miles away.