[Asterisk-Users] ISDN X-Over

[Stefan Märkle]

> David J Carter schrieb:
> > Hi all,
> > 
> > I have just been reading an article on the asterisk-doc site about 
> > ISDN X-Over cables.
> > 
> > The article mentioned the converting of an NT1 to make this 
> possible, 
> > has anybody got the information required to modify a BT NT1?
> > 
> > Or any information on the BT NT1.
> 
> As far as I know, you just need a second ISDN card and a X-cable. No 
> mods to the NT1 are needed. To build such a cable, just swap 
> the outer 
> pair with the inner pair.
> 
> 3 ----- 4
> 4 ----- 3
> 5 ----- 6
> 6 ----- 5

In Addition, you need bus termination:
- Use a device that terminates the bus
  * Your NT1 does that (often already enabled with dip-switches inside), just plug the x-over to the nt1 as well as your other device(s)
  * Use a multiplug that terminates the bus
- or just put in two 100 ohm resistors, one between 4&5 one between 3&6. Extremely easy and cheap if you cut a cable in half, rewire them using a screw joint, where you can also put the resistors in.

Depending on the device you want to connect, you might need bus powered, THEN you really need your NT1 (or a card that provides this feature). Link to PBX4Linux - documentation has already been posted.


Greets
Stefan


-- 
Stefan Märkle                       Netpioneer GmbH
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<stefan.maerkle at netpioneer.de>      76137 Karlsruhe