> Since when you close the Relay, the line is shunted by a low
> resistor, high ring voltage will cease in that moment

I've seen a couple of instances (user circuit and app note)
showing 220R switched directly across the line. Neither of
those use an isolating transformer. In my application would
this mean then a 2PCO with one pole on the line side to
switch that resistor in ?

> I'd count some rings anyway before closing the relay :)

Yes, that's sensible. Was reading a Scenix app note outlining
s/w ring detection which rejects noise events, and had planned
a couple of timed rings

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist