Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

PRI & ISDN Network

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 will 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 the main office 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.

Thank you for your cooperation.


Hall of Fame Super Silver

Re: PRI & ISDN Network


In my experience increasing the idle timeout does not help to solve this problem. And in my experience if you do not want the branch to initiate the call the best solution is to remove the phone number from the dialer map on the branch.

The issue is that to bring up the ISDN there must be "interesting" traffic. And if only the main office has a number to dial then the interesting traffic must originate from the main office. Depending on how you have configured the dialer map and the dialer list that interesting traffic could be ping or could be other kinds of traffic.

Depending on the characteristics of the traffic between the branch and the main office your solution could work well or it could not. If most of the traffic is transactions initiated from the branch then your implementation is problematic. User initiated traffic from the branch can not bring up the ISDN if the branch has no phone number for the main office. So user traffic must wait until there is some traffic from the main office (like the ping that you mention).

In the situation where you do not want the branch to initiate the ISDN some people will not configure the dialer list. This is problematic because without a dialer list at the branch there is no interesting traffic from the branch and so the idle timeout will bring down the link even if users are attempting to send traffic.



Re: PRI & ISDN Network


In this case you need to specifically configure dialer interafaces for each respective sites and configure the dialer string and all other dialer related information so that the pri line dials out and the remote locations just recieve the calls.

You need to tweak the config at the far end as well to make sure that u recieve the calls from the central location.