> Phone line.
>> Yes !!!
>> Constant current source ! :-)

> Seriously - is it? How many mA? Maximum voltage? Useful information if I
> ever need it.

Approximates constant current.
Value will change with line length and situation.
Some circuits will shut down if shorted.

Looks like about -50 Volts wrt ground for central office phones. PBC
are often 50V but also may be less.

Probably 100+ mA up close to CO (Central Office)
Custmer line can be 1000 Ohm so at 50 V that alone would limit  I to 20 mA.
Safer is to assume it is over current regulated 50V supply.

If line is not to be tripped to off-hook state allowable current is
low . Under to well under 1 mA.

>> Whipping up a GSR would give about 10:1 charge boost into a single

> What's a GSR?

"God's Switching Regulator".
But a fair ring in is seen here

      http://sound.westhost.com//appnotes/an006.htm



      R
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