re need to find out number to a phone line alee ecs umass edu writes greetings situation i have a phone jack mounted on a wall i don t know the number of the line and i don t want to call up the operator to place a trace on it question is there a certain device out there that i can use to find out the number to the line thanks for any response al there usually is a way however often telephone companies like to keep all of their internal numbers private depends on your exchange any modern electronic switching equipment usually have voice synth lines that echo the number you called from the line service guys use this to make sure they connect up the right pairs of lines
