[Asterisk-Users] Re: Shielding of T1/E1 cables WAS RE: Pinoutsfor T1/E1 crossover

[Rich Adamson]

Andrew Kohlsmith wrote:
> On Monday 24 April 2006 16:13, Rich Adamson wrote:
>> A 'real' T1 cable would use a twisted pair for pins 1 & 2 and another
>> twisted pair for 4 & 5.  Looks like a typical cat5 straight-through
>> cable uses twisted pairs straight across pins 1 through 8.
> 
> Nope.  A cable wired for ethernet and a cable wired for T1 are wired 
> *identically*:
> 
> Pair 1: Pins 4&5
> Pair 2: Pins 1&2
> Pair 3: Pins 3&6
> Pair 4: Pins 7&8
> 
> Where the difference lies in what pairs are used.  T1 uses pairs 1 and 2, 
> while standard 10/100 ethernet uses pairs 2 and 3.  This is why a T1 
> crossover and an ethernet crossover are not the same cable, but a T1 patch 
> and ethernet patch are.

Cool!

Guess you can tell how many times I've actually wired a cat5 cable. ;)

The only issues open relative to using cat5 cables for T1 runs is the 
impedance and shielding. Guess we pretty much beat those into the ground 
as well.

R.