I have very strange problem, and hope someone out there has an idea how
to fix it. I have a 2-line phone, but I get a loud hum on line #2 when
I have both lines plugged into the phone. When just line #1 is
connected, the signal is very clear. I am pretty sure that the problem
is inside, since I've checked each line at the NIC outside, and both
are clear. I have replaced the standard twisted pair wiring with
cat-5, but that hasn't helped. I thought it was the phone and had that
replace, but that didn't fix it, either. Any ideas? Thanks
unplug the problem phone overnight from phone line and any power
adapter and remove its batteries, to discharge any surge problems, and
check it the next day. compare it to a known good phone. phone
telephone repair and have them test each line. try two single lines at
the same problem jack and see if there is crosstalk. check the lines
for a high resistance short with a megohm meter. reverse the line
pairs. reverse the red/green polarity. reduce the phone to one line
use. remove other items on the lines like computer, fax, caller id
Looks like most of the troubleshooting has been done. The question I
have is were both incoming CO lines at the NIC plugged into the phone
the same way it was in the house so that the test was a true test
duplicating the in-house set up (as opposed to testing the two lines
independently)? Normally a jack is wired to the RJ14 standard for two
line sets, but I have seen a few phones that put line one on one jack
and line two on another so that the phone uses RJ11 instead of an RJ14
set up: http://en.wikipedia.org/wiki/RJ11%2C_RJ14%2C_RJ25
If the lines are good at the NIC and work when plugged into the phone
like they were in the house and the problem goes away, then you pretty
much have identified the problem as an inside the house problem if the
exact same phone was used. New wires installed and pinned out properly
and problem is still there? New jack too? If a new wire was installed
AND a new jack was installed too (from the NIC or a cross connect point
in the house?) and the problem is still there, then it would seem like
a phone problem, but the E-mail says new phone was used too.
Does the phone have features that require a plug in power supply?
Perhaps the problem is power related at that location. Bad ground
issue? Sometimes a hum is caused by the line touching ground somewhere
or sometimes a proper ground missing from a business phone system
causes an open ground hum.
Will phone work without plug-in power supply, then try with power off.
That's my 2-cents.
Carlos M. Mendoza, Jr.
Data - Video - Voice - Fiber Optics
Office: (716) 831-9799
Fax: (716) 831-7073
Cell: (716) 445-1537
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