is there any special divise to connect ISDN and from that devise it is seperated 2 different PABX? 1 is a working PABX and another one is a backup PABX so that if the working PABX goes down I can manually switch the devise so that the ISDN works for the backup PABX......pls advise.

Perhaps an Adtran Atlas would do something like that, but would cost quite a bit, as I think they start around $5000. Also, probably overkill for what you want to do.

Can't you just run another cable from the backup PBX to the csu and then plug it in when you need it?

[This message has been edited by phonemeister (edited June 17, 2004).]

simple solutions are usually the best
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There are proprietary cards made for certain PBX models that automatically switch an ISDN line, but very pricey. You didn't mention which PBX. If you want to transfer manually, I would just try a simple DPDT switch, mazking sure the twists in the wire are close up to the connector, to avoid loss of digital signal. If the distance isn't to great between the PABX's it should work.