On Sunday, June 22, 2014 12:17:07 AM UTC-4, Stephen Sprunk wrote:   
   > On 21-Jun-14 22:33, hancock:   
   > > I have no idea what the voltage/currents are on VOIP phone lines.   
      
   > On the POTS side, both should be the same as a real POTS line.   
   > On the IP side, it's whatever the relevant IP technology uses, but in   
   > general the longer the wires it's intended to run over, the higher the   
   > voltage (at least at the source) will be.  Most use differential or   
   > alternating signaling so the net current is zero.   
      
   At some offices, there are various types of phone landlines.  One is the   
   traditional analog.  Another is 'digital' (POTS telephone sets will not work   
   on it).  Still another, the newest type, is VOIP (no POTS phones either).  I   
   don't know the difference    
   between 'digital' and 'VOIP'--indeed, I thought the two were the same.   
      
   Anyway, as mentioned, plugging in a voltmeter to a traditional landline yields   
   48V DC.  I have no idea what voltage will be given if plugged into a 'digital'   
   or 'VOIP' line.   
      
   Returning to railroads, into the 1980s it was common for some lines to be   
   served by handcrank (local battery) telephones.  Simple and rugged.  I think   
   they're all gone in the US.     
      
   --- SoupGate/W32 v1.03   
    * Origin: LiveWire BBS -=*=- UseNet FTN Gateway (1:2320/1)