We actually bought some years ago but never got round to using them. I
still have two brand new bells, pulleys and a 'pull'. From CH Byron, who
now seem to have been subsumed into 'Smartwares' and don't do much of
that any more.
Instead, we now use a conventional doorbell push which pulls an input on
an Arduino, which in turn sends a signal to a daemon on the Asterisk box,
which then queues immediate calls to ring all the phones in the house
with a special cadence. Optionally, it can ring a bell in the garden
(controlled by a star code). It's also possible to limit doorbell calls
to the two teenagers' rooms for a fixed time (default 30 minutes) so that
the 2 a.m. pizza deliveries don't wake us up.
I wouldn't have dreamed of this when we bought the mechanical bells in a
fit of enthusiasm.
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