sundance-communications.com/forum Forums Wiring - Telecom Carriers - Trunks & Services Telecom Service & Providers Hum on POTS line

Hi, I'm new to the forum. I'm hoping someone can help me figure out what is going on with this hum. The hum is on my parents' phone line. I can hear it when I call them, and when I am at their house and use their phone, I can hear it. It's not especially loud, but it is there and it is annoying.

Long story only slightly shortened ...

When I was home for Christmas I called Qwest about it and they got a tech out there the next day. He said he cut us over to a different pair of wires. I led him to the NID and he hooked up his butt set. No hum. He hooked up some tech equipment and he said the line checked out fine and was within noise specs. He even used an adapter to hook the set into the house wiring and let me listen and there was no hum on his set that I could hear. So it's not the house wiring. I handed him the $150 panasonic cordless phone and let him listen. He heard the hum but he said he thought it was because it's cordless. But the corded phone in the house has the exact same hum.

With the Panasonic on its lowest volume setting you almost can't hear the hum when calling out. (But if you're on the other end you can hear it faintly.) Turn the volume up and you definitely hear it. The corded phone (no volume adjust) you can easily tell it, although it's not loud enough to keep you from conversing. By the way, this corded phone is brand new. It's no different when you plug directly into the NID.

Another symptom worth pointing out is that before DSL was available, I would do dial up Internet. I would bring my notebook computer home with me and would only be able to connect at 24K or 26K bps. It would sometimes lose the connection. However, at other locations I would routinely connect at 48K or 51K with the exact same modem!

So why can't you hear it on a butt set? Are they much different than a consumer phone? I'm going to have to diagnose this because as far as Qwest is concerned, there isn't a problem, because they don't hear it on their equipment.

I hope someone can help. Thanks!

A butt set really isn't all that much different than a regular telephone. There is some circuitry inside that will allow the technician to make sure that a telephone line isn't wired "backwards" and maybe some built in circuitry that allows the technician to test a telephone line with DSL service without causing the DSL signal to drop.

Hum is sometimes caused when one of the two wires that make up a telephone line are broken or if there is a partial ground condition on the telephone line.

To determine if the problem is being caused by one of the telephones, have your parents unplug all but one of the telephones and then make a test call. If there is hum, disconnect that telephone and connect another telephone. If no hum, either the first telephone or the wiring to that jack is bad.

If you still hear the hum, then it would appear that Qwest still has a wiring issue that needs to be resolved.

If your NID is modular, try taking the phones & plug them directly into the NID. This will determine if the trouble is with Qwest, or, if it is internal, ie, the phones or the wiring/jacks.

If the house is an older one, there is a slight chance that there's a dial light transformer on the premises from the old days. These were used for Princess and Trimline phones in the 1960's and 1970's. They were wired to a separate pair of wires (usually the black/yellow) in quad wire. This induced 10 volts AC into a piece of wire that is not twisted pair right along with the dial tone.

These transformers are usually gray in color, have rounded corners and plug directly into an electrical outlet ANYWHERE on the premises. You might want to check for the presence of one of these. If you find one, you should remove it and discard it. They are no longer used.

SBC's wiring is 99% twisted-pair, with the possible exception being the final drop wire to the house. If the technician changed the address to another pair, then it's safe to assume that the problem is in-house. Most newer phones are much more sensitive and will pick up the slightest imperfection in the inside wiring.

Check and see if the base of the phone is next to a fluorescent desk lamp.

Believe it or not, this has been the cause of two separate calls I've been on recently involving a hum.
I'm sure that the guys that already replied are right, they've probably forgotten more than I will ever know about this business, but it doesn't hurt to check the small stuff too.

These transformers have also been know to overheat, and cause fires, giving another good reason to remove them.

Had one in just the past couple weeks where a calculator plugged in next to phone caused a hum. Computers have an effect sometimes,too.

Scott.

Thanks for all the responses. I had been so busy last week, I didn't even get a chance to respond. In fact it is a modular NID. Before I called Qwest, I went and plugged a phone into the NID and I still heard this hum.

The house was built in the mid 1980's. The telephone wiring is standard 2-pair, 2 phone line capable. It was installed in about 1985 by Northwestern Bell/US WEST. From talking to the Qwest tech, it is still copper all the way to the CO.

But the thing I was wondering about is that the phone line comes in, and is in fact taped to electrical service (conduit) that runs from the main breaker box to a smaller one in the garage, rated at 100 AMPS, 240V AC. The NID sits inches away from the main breaker box. My father is an engineer and loves to overbuild things, so the incoming wiring is big. The main breaker is 400AMPS, 240V! I keep thinking that the hum could be coming from there, but I'm not sure how I can check, since there is nowhere to tap into the phone line outside the house.

By plugging a regular corded phone in at the NID and still hear the hum, you've eliminated the inside wiring. Not sure why it wasn't heard when the Qwest tech was there the first time but plugged directly into the jack in the NID the noise has to be coming from the Telco network.

Tell your telco tech to test for low (8 10 volts of ac induction along the underground cable. The 'average" telco tech (now a days) will walk up to the SNI, hook up buttset, if it 'sounds good' trouble in inside and he closes out his ticket.(This increases his hourly productivity.)