Phone system notes
From Helpful
Contents
Mobile style
See Electronics notes/Cell phone notes
Landline style
POTS usually refers to Plain Old Telephone Service - often meaning in context of phones or acoustic modems, and in the last case often in contrast with broadband internet.
https://en.wikipedia.org/wiki/Plain_old_telephone_service
PSTN (Public switched telephone network) carries a similar meaning.
https://en.wikipedia.org/wiki/Public_switched_telephone_network
Connecting phones or modems together
Hybrids
Dialing
Devices on a line
https://en.wikipedia.org/wiki/Caller_ID