[Asterisk-Users] False RING (incoming call) on Digium X101P FXO

[Don Pobanz]

On Saturday, September 20, 2003 10:37 PM, Mark Spencer 
[SMTP:markster at digium.com] wrote:
> > I was surprised to see that it's 240 volts (peak-to-peak)!  Egad..
> > no
> > wonder it shocks fingertips.
> >
> > 20Hz (50ms cycle), 2 second long clean sine waveform.  I was just
> > surprised to see twice as much voltage as expected.
>
> 240 sounds like a lot.  Are you sure you were doing DC measurement?
> Normal is +/- 90 - 120, generally at least 48VRMS or about 70V.

The local phone company will, while the phone is on hook, provide a 48 
 to 52  dc voltage at the central office. To ring a phone a 50 v ac 
signal is placed on top of this ~50 v dc.

Don Pobanz

>
> Mark
>