[asterisk-users] Problems Connecting Two Asterisk Installs Via ISDN PRI Cards

[Tony Mountifield]

In article <46F41BFD.1000200 at drdos.info>,
Doug Lytle <support at drdos.info> wrote:
> Tilghman Lesher wrote:
> > A straight-through cable to used for connecting from a QuickJack to a T1
> > card, but a T1 crossover is needed for card-to-card (or card-to-channel bank,
> > for that matter).
> >   
> 
> I have a Sangoma 102u port 1 to port 2. 
> 
> And, my Micoscanner is showing
> 
> 1  --  5
> 2  --  4
> 4  --  2
> 5  --  1
> 
> So I went and made a new cable with the
> 
> 1  --  4
> 2  --  5
> 4  --  1
> 5  --  2
> 
> The Sangoma worked with that as well.
> 
> Interesting.

1&2 is one twisted pair, 4&5 is the other twisted pair. The difference
between the two configurations above is just that the polarity of
each pair is reversed at one end, which in this case doesn't appear
to matter. Each pair is carrying a balanced signal.

Cheers
Tony
-- 
Tony Mountifield
Work: tony at softins.co.uk - http://www.softins.co.uk
Play: tony at mountifield.org - http://tony.mountifield.org