Telecommunications Tech Blog June 2013
Fixing Crackling Static on an Analog Phone Line or Analog Station Port
By Mike Sandman •
Crackling type static on an analog phone line is caused by
a bad connection (high resistance) or a short to foreign voltage / ground.
In the old days it was often caused by the open
(un-insulated) telephone wires running between insulators on telephone poles
swinging in a strong wind, occasionally touching a wire from another telephone
line. That was called a "swinger."
A more serious problem that also caused static was when
one of the telephone wires touched a power wire. The current from the power line
going into the phone line can cause fires and serious bodily harm. It can still
You don't hear crackling static if you have a bad
connection on the speaker wires from your stereo. That's because there is no DC
on those wires. Only AC audio. When there is a bad connection or short on your
speaker wires you hear the volume go down - no static.
If you're hearing static on an analog phone line or
station port the cause of the problem has to be fixed, there is no filter for
Some people call data noise, often picked up inductively
from nearby computer equipment, static. There's a big difference in the
crackling static caused by a bad connection or a short and data noise (which is
more of a consistent hiss or humming sound).
If the problem is at the demarc with the inside wiring
disconnected the phone company has to fix it. If the problem is inside you have
to try a spare pair or replace the cable.
It's harder to fix an intermittent problem that might only
happen in bad weather!