[geeks] nerd reading for a Friday night ... old-skool waxed twine lacing

[James Fogg]

> Neat!  It works fine plugged into my POTS line.

Yup, it will work fine. The R (release) button is a hookflash signal
used to access features of a PBX. The LED shows when a caller is on hold
or parked (in orbit).

The release button isn't much different than a "flash" button on a
modern phone, though it should be very precise in the timing of the
hookflash.

If you wanted to pay a lot of money for Centrex service, you could have
a PBX-like phone system in your house using phones like that black 2500.
Centrex is basically the phone company providing PBX services via a
bunch of subscriber lines to a small business. Each desk phone is a
separate subscriber line.