"Dave Plowman (News)" wrote in message
...
In article ,
Andrew Gabriel wrote:
You can't simply swap them. The jack plugs run the phone bells in
series, and you'll need to change the circuitry for parallel phone
operation,

The strange thing is they don't. On that plan the bells were in parallel -
otherwise you'd have needed some form of switch when one was unplugged.

The bells are in series. There is a set of contacts in the jack that form a
switch when the plug is unplugged.