On Wed, 2 Jan 2013, ned+ietf(_at_)mauve(_dot_)mrochek(_dot_)com wrote:
At one point there was something that said one phone in each home had to be
directly wired without a plug. I don't know if this was a regulation, a phone
company rule, or just a suggestion, but it also fell by the wayside after
Carterphone.
May have varied by baby bell, but in Michigan, you could have as many
jacks as you wished, but you had to lease them all from the telco. There
may have been a rule about having at least one hard wired phone, I don't
recall. In those days, the telco owned and was responsible for all inside
wiring.
I certainly saw acoustic coupled equipment in use long after Carterphone, but
in my experience it was because of general intertia/unwillingness to do the
necessary engineering, not because of the lack of connectors.
Probably more to do with portability of accoustic couplers and the lack of
provisioning in motels, etc. for jacks.