Art Allen, KY1K wrote:

> Yes, the circuit and explanation is shown @
> http://209.1.238.246/1st_pages/A1208.htm
> The chip is a max638 and it looks like 50 ma @ 5v regulated can be
> drawn from the line when the phone is not in use.

  It is made quite clear in the above article that *no* power can be
obtained from the telephone line in the "on-hook" state.

  The circuit's specific purpose is to derive a 5V supply using the SMPS
chip, from the line current *while* the device, be it a speakerphone or
a modem, is "off-hook".

  It's just an application note on a 12V to 5V switchmode down-
converter.
--
  Cheers,
        Paul B.