TELECOM Digest OnLine - Sorted: Re: Cross Battery and Verizon

Re: Cross Battery and Verizon

William Warren (
Fri, 17 Dec 2004 20:11:10 GMT

On Wed, 15 Dec 2004 14:01:52 GMT, Joe Perkowski
<> wrote:

> Hey ppl,

> Does anyone know what is "cross battery"? We put in a NBX 2 months
> ago running fine. Now, we are getting static and crosstalk on some of
> our incoming lines.

> We have had a great deal of rain these past 2 weeks, and have had
> previously problems with Verizon due to old copper in our area.

> The Verizon guy is telling us "cross battery" is causing this?

> What is "cross battery" if anyone knows...?


He means "Crossed _WITH_ Battery", i.e., he sees a "foreign" voltage on
your pair when he puts a voltmeter on your line at the CO.

There are three possible causes:

1. The pair is defective, and is shorted to another pair in the
cable. The tester is seeing the voltage on the _other_ pair (-48v from
the CO), looped back to him through the short circuit in the cable.

2. There is a short circuit in your company's internal cable.

3. Your PBX places a "Ground detect" voltage on the pair in order to
sense the tip ground which signals dial tone on a ground-start line.

In all these cases, you'll need to open the lines at the demarcation
point and make a binary decision about which side (your or theirs) the
problem is coming from.

In case (3), if your test at the demarc shows voltage coming from your
PBX, the problem could be that your PBX is optioned for ground-start,
but the CO is configured for loop-start. You'll need to change the
options on the line(s) involved.



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