ISDN & PRI Network problem

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Jan 29th, 2010
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I have an ISDN network as the following:
In main office PRI link.
In the branches BRI links.
see the attached.

I want only the main office which make the calls not the opposite.
I want the cost to be on the main office

I increased the idel-timeout and delete the string (telephone no.)in the branches so if the branch need to call he can't because there is no No. to call so only the main office able to call.

But, the problem when the router in a branch turn off there is no connection until the main office makes ping to make connection setup.

Do you have a solution for this problem instead of increasing the idel-timeout and deleting the telephone no. from the branch's router.


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Phillip Remaker Sun, 02/21/2010 - 08:47
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  • Cisco Employee,

So it sounds like the branch offices originate the traffic, but you want the main office billed.  Does the PSTN offer "reverse charge" calling?  Some PSTNs allow that.

You don't want the link up all of the time, I assume?

What you want is "ISDN caller ID callback."

You can set up ISDN so that the branch office calls the main office, but the main office always rejects the call.  Most PSTNs do not charge for a rejected call.

However, when you reject the call, you can see the calling party ID information, and you know that the branch office wants to talk.

You can set the main office so that on detection of the call, the main office will call back the branch.

Docuementation for ISDN caller ID callback is at


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