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Configuring Backup PSTN for Distributed over IP/WAN Single Cluster

I have a configuration with CCM 3.3 in two (2) cities. We need to have the ability for users dial a single phone number (5 digit dialing) and have the call rerouted across the PSTN (VG200 is being used as the PSTN Gateway) IF the IP/WAN goes down.

Does anyone have a soultion to this problem?

Thanks for your help!!

Regards,

Larry

8 REPLIES
New Member

Re: Configuring Backup PSTN for Distributed over IP/WAN Single C

Hi Larry,

You can prefix digits to outgoing calls for the route pattern associated with the PSTN gateway.This is very easy to do in callmanger .

You might have to configure this on the gateway in the route group which is second choice PSTN.

Bronze

Re: Configuring Backup PSTN for Distributed over IP/WAN Single C

Im assuming you already have an ICT between the two cities, and have a Route Pattern that allows for 5 digit dialing across the WAN. If this is the case, then you will need to create a new Route List, and 2 Route Groups. Put the WAN gateway in 1 RG and the PSTN gw in the other. You can then define which gateway is tried first, and specify what digits to add/discard per gateway.

This will failover the call to the PSTN automatically, so the users dont have to dial another number.

New Member

Re: Configuring Backup PSTN for Distributed over IP/WAN Single C

Thanks to all for your suggestions!!

I should clarify the configuration that I am running.

I have a Distributed Single Cluster call processing deployment.

The Publisher is in one city and the Subscriber is in the other.

Both CCMs have primary loads and back each other up as secondaries.

The phones have 5 digits assigned (directory number). I can call from site to site (city to city) using 5 digits (DNs) across the IP/WAN (ICTs are not used).

I need to access the PSTN if the IP/WAN goes down and this must be transparent to the users.

I am trying to configure AAR a solution and WELCOME any other ideas!!

Thanks for your help!!!

Larry

Re: Configuring Backup PSTN for Distributed over IP/WAN Single C

Larry,

AAR may work but why not try using a translation pattern for all the incoming numbers that has a search space that looks for the phones in one partition first first, but then when it can't get them it uses another translation pattern that dials out to the PSTN.

Something like.

incoming_partition has a translation-pattern ! which can access CSS_incoming_calls

CSS_incoming_calls contains partion_internal_extensions and partition_PSTN_redirect

Partition_internal_extensions contains all extensions

Partition_PSTN_redirect contains translation pattern 12345 can access css_external and the transformed number is 9121232312345

Paul

New Member

Re: Configuring Backup PSTN for Distributed over IP/WAN Single C

Paul,

I think there may be a problem here. The phone will find a match for the digit string, however that phone will be unavailable (i.e. WAN is down and the phone is located on the other CM server in the same cluster across the WAN) and so CM will follow the CFNA destination for that device and will never make it to the second match which is the Translation Pattern that was set up.

I would love to test this, I think that is how it will behave. We need a feature to forward the call to it's DID Number via PSTN on Failure.

Cheers,

Jim

New Member

Re: Configuring Backup PSTN for Distributed over IP/WAN Single C

I'm afraid I don't understand what you mean by "Both CCMs have primary loads and back each other up as secondaries". Do you mean that phones are homed to the local CCM as primary and can rehome to the remote CCM in case the local CCM is unavailable?

New Member

Re: Configuring Backup PSTN for Distributed over IP/WAN Single C

Hi Larry

I am also interested in this topic. Have you done the test for AAR?

I came cross an article mentioned that you can use digit translation rule on the GW to fix this .Here is the link of this article and see the digit translation section which specificly talking about this. http://www.cisco.com/en/US/partner/products/sw/iosswrel/ps1835/products_configuration_guide_chapter09186a0080080aec.html#1248770

Only thing I am concerned is whether the system will do the translation even the WAN is no problem. Which means calls always go to PSTN even WAN is good. I am not sure this part. Has anybody can share experience?

New Member

Re: Configuring Backup PSTN for Distributed over IP/WAN Single C

Thanks for your reply!

Yes you are correct.

as an example:

Phones in city A have CCM-A as the primary CCM.

Phones in city B have CCM-B as the primary CCM.

If CCM-A goes down then the phones that it normally controls will rehome to CCM-B.

or

If CCM-B goes down then the phones that it noemally controls will rehome to CCM-A

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