asterisk users - Apr 2005 - Ringing problems was TDM400P Revision question.

Rich Adamson responded to an earlier reply (not from me)
> Eric, those links have nothing to do with his stated problem. The
> problem is "105v AC on the pstn line when on-hook and no
ringing".
No, he says the issue is about ringing and strange voltages on his 
Digium TDM400 FXS ports, not the PSTN line. He measures 107 VAC on the 
line with the phone on hook and not ringing. Are we sure this is 
measured across the line and not from one side of the line to ground?

If there were 107 volts AC on the pair, and there was any current 
available, the phone would ring all the time. Since it doesn't, it's 
likely to be a faulty meter or (more likely) a high resistance ground 
fault in the PC power supply providing a sneak path for a few microamps 
of power line voltage to get to the pair. Check grounding of the PC case.

The basic problem however is that (assuming the meter is right) there is 
only 45 volts during the ring interval. This is not enough for most 
ringers. Try boostringer=1 as suggested by the last response and check 
the ring voltage then. Many ringers need at least 75 volts to function 
properly.