I was having an issue with a pset line; I had the provider come over several times to fix the line and could not get it to work. I tone the line without fail and also detected no shorts. I know the pset lines required a 3 pair perfect line setup (3 pairs; voice, data, and power). When the provider told me it was an cpe issue I requested their best tech to meet me at the site. I took the tech to the dmark and I plug a working pset phone (muitple working pset phone where used) to the line facing the providers CO, no dial tone. Yet the tech plug his pset tester I and was able hear a dial tone, yet no pset phone was able to work. The tech did not know what to tell me except that it was both a CO and a inside line issue. After repeated arguments with the provider that it is a line or cpe issue. I decided to switch the cross connects and disconnected the pset line. I then connected a working analog line to the users jack and told the user they can deal with a simple analog phone. No problems with the line after that.