35 yrs ago today; The Bell System is broken up

[sl8]

5. It helped pave the way for better and cheaper modems.

From Wikipedia, https://en.m.wikipedia.org/wiki/Acoustic_coupler

...

Prior to its breakup in 1984, Bell System's legal monopoly over telephony in the United States allowed the company to impose strict rules on how consumers could access their network. Customers were prohibited from connecting equipment not made or sold by Bell to the network. The same set-up was operative in nearly all countries, where the telephone companies were nationally owned. In many households, telephones were hard-wired to wall terminals before connectors like RJ11 and BS 6312 became standardized.

The situation was similar in other countries. In Australia, until 1975 the PMG, a Government monopoly, owned all telephone wiring and equipment in user premises and prohibited attachment of third party devices, and while most handsets were connected by 600 series connectors, these were peculiar to Australia so imported equipment could not be directly connected in any case, despite the general electrical compatibility.

It was not until a landmark court ruling regarding the Hush-A-Phone in 1956 that the use of a phone attachment (by a third party vendor) was allowed for the first time; though AT&T's right to regulate any device connected to the telephone system was upheld by the courts, they were instructed to cease interference towards Hush-A-Phone users.[1] A second court decision in 1968 regarding the Carterfone further allowed any device not harmful to the system to be connected directly to the AT&T network. This decision enabled the proliferation of later innovations like answering machines, fax machines, and modems.

...

More at link.