[asterisk-users] fxotune question

[Tilghman Lesher]

On Monday 09 June 2008 12:27:39 Drew Gibson wrote:
> I thought I had found something, all of the lines were patched in with
> Cat 5 patch cords except Port 16 which had a telephone cable (which
> would flip the polarity). After changing all the patch cables to
> telephone type, I re-ran fxotune but the results were almost identical
> to the original settings.
>
> new fxotune.conf:-
>
> 13=7,255,251,251,2,255,255,1,255
> 14=9,254,251,255,2,0,1,0,0
> 15=6,1,254,253,0,255,0,0,0
> 16=5,0,0,0,0,0,0,0,0
> 17=9,254,251,255,2,0,1,0,0
> 18=9,254,251,255,2,0,1,0,0
> 19=9,254,251,255,2,0,1,0,0
> 20=7,255,251,251,2,255,255,1,255
> 21=9,254,251,255,2,0,1,0,0
> 22=9,254,251,255,2,0,1,0,0
> 23=6,1,254,253,0,255,0,0,0
> 24=9,254,251,255,2,0,1,0,0
>
> These results are very similar to John Morey's, eg. not much changed
> after reversing polarity.
>
> The one line that shows zero's all the way across is the line with our
> DSL backup line on it. Is it the filter giving these results or does the
> telco take more care balancing lines for DSL?

The telco takes a lot more care on these lines, since if there is echo on the
line, the DSL will not negotiate a connection correctly.  Since it was clearly
a different wire than the rest of your plant, you might trace your wires out
to the demarc and see if there's damage somewhere along the line.  It could
also be that there is damage beyond that point, but you'd need a telco tech
to trace that out correctly.

> Shouldn't I have seen a major change of settings after changing polarity
> for tip&ring?

I thought so, but Matt F would be the person to ask about that.

-- 
Tilghman