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New Member

PSTN backup in centralized CCM cluster

Centralized CCM with 1 remote office. Remote office area code is 705.

Users in HQ can make toll free calls 705xxxxxxxx to remote office via data network, vice versa. My questioin is: if data WAN failed or bandwidth exceeds number of calls, will the system automatically route the call from PSTN as a long distance call, or user have to manually dial 1705xxxxxxx?

I recall that some documentation indicates that if router running MGCP, it has this feature, but H323 doesn't. is this true?


New Member

Re: PSTN backup in centralized CCM cluster

It depends on how your dial-plan is setup.

Here's how I would do make this work.

I would create a Route List, call it RL_Tollbypass. Create a Route Pattern 9.@ where area code = 705 and point it to the RL_Tollbypass Route List.

Next I would go to the RL_Tollbypass configuration and add the Route Group that contains the gateway at the remote site and set the DDI to PreAt.

Then I would add whatever Route Group contains the gateway with pstn access at your HQ site to the RL_Tollbypass Route List and set the DDI to PreAt and set the prefix digits to 1.

So now when a user dials 97055551212, the call will be routed to the RL_Tollbypass route list, then if the WAN is up the 9 will be striped off and the call will be routed to the RG_RemoteSite as 7055551212. If the WAN is down the 9 wil be stripped off, a 1 will be prepended and the call will be routed to the PSTN as 17055551212.

You could go one step further and add a couple more Route Patterns that would match the call regardless if it was dialed as 10 or 11 digits and try and send it to the remote site.

hope this helps.


Tim Medley, CCDP, CCNP

IPT Consultant

New Member

Re: PSTN backup in centralized CCM cluster

That's very good. I was trying hard to get this information from CCO but no result.

Thanks a lot.

Btw, how about PSTN fallback for IP phone to IP phone between remote office and HQ when WAN went down? It seems we are not able to use this solution because it apparently there is no route group needed for intenal calls . How do you fix this?


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