June 20, 2007

A buzzing on my phone

....when called by a client's ISDN phone.

She sits in an office, about 180 feet from the Telephone terminal room. She has an ISDN telephone, same as two others in the office next to hers. She has a medium loud 60 hz buzz on her phone, audible to both her and the other party, not so loud as to make conversation impossible, just rather annoying.

The underground is cross-connected to the input of a rack mounted NIU. The out of the NIU is cross-connected to a block feeding jacks in the cat-5 patch rack. As is the -48vdc power for the ISDN phone. At the patch jacks a short patch cord connects to the Cat-5 cables going to the office.

The phone has been swapped out. No to mention that if I plug it into the jack coming from the NIU I have no noise whatsoever -- you can ask my wife!
(trouble is NOT is the terminal equipment, the phone itself)

Things that did not stop the buzzing:

Patch to the old 25-pair cat-5 cable on the opposite corner of the office.
(trouble is NOT is the cable from the terminal room)
Run the U-interface to the office and provide stand-alone NIU/power.
(trouble is NOT is the rack mount power/NIU)
Put a long (30') cable into the jack in the office and walk about with the phone.
(trouble is NOT is induced at or near the desk)

This trouble is starting to bug me.....

Posted by Paladin at June 20, 2007 03:07 PM
Comments

Hi Mike,

Regarding trouble ticket BS066152 ISDN 310 783-7943. 21281 Western Rm.110, Torrance. I have two advisors I go to when I'm stuck on an ISDN case of trouble, they are:

Ken Pulverenti (KP1652) and Mike Mead (MM6871) .

Thanks for your help!
Val
VS3212

Posted by: Valencia Suggs at June 20, 2007 03:59 PM

Did you swap out the NT1 to see if it's the cause of the noise?

Posted by: Ken P at June 21, 2007 08:15 AM

Not only swapped out the NT1, switched from rack mount in the terminal room to a stand-alone in the client's office -- which also meant extenting the U-interface (2w) from the underground to the office rather than the ST-interface (4w) from the terminal room. At the same time the power to the telephone was changed from rackmount to standalone so that the only thing happening in the terminal room was a jumper from the underground to the floor cable.

Posted by: Paladin at June 21, 2007 10:26 AM

As I understand you already localized the U-interface and put the NT1 in the office location with no affect. I am to assume it is specific to the enviorment within the office. Try putting a long cord on another key set and bringing that ckt into you users office and see if the condition duplicates. Try shutting off all of the lights in that office. I have see a bad ballast emit RF and induce such 60Hz noise.

Posted by: Mike Mead at June 21, 2007 01:56 PM

Ah HA!!!

Ken (on the phone) pointed out that I had always ran thru the cat-5 patch panel. So I again re-ran the line, from the MPoE, a single cross connect wire to the floor cable, out of the floor cable into the power adapter, thence to the NT1 and to the phone. BUZZZZZZZ!

As I said, we did swap out the 'phone -- but it was like for like -- a new Lucent i2021. So I grabbed a Fujitsu 9924 and it was *QUIET*.

History -- the noise started when the client moved from the 21241 building to the 21281 building. Rather than simply do an outside move of the cable pairs to the THEY (the same mysterious THEY that always causes the problems) went and completely rebuilt the service on new office equipment.

The problem cannot be anything BUT a problem in the O.E. -- either the O.E. itself (doubtful) or an option. And in any case, not my problem.

Posted by: Paladin at June 21, 2007 02:02 PM