How to route calls through PSTN when WAN connection goes down?

[lynxul]

Hi All!

I have a few offices around the country that we call via the MPLS line. Problem is when the line goes down the call just ends nowhere.

How can I automatically reroute the calls through PSTN based on the number listed in Call manager?

I'm using Cisco Call Manager 4.1 with 2821 and 2801 voice routers.

Thank you!

 

[pndscm]

What you are talking about is called Automatic Alternate Routing (AAR) and it should be available in your version.

Google it and you should be able to get step by step directions from CCO

 

[lynxul]

I may be wrong but I think that AAR is only used for counting the number of calls, multiplying it by the call bandwidth and when the result is over the definded bandwidth it will redirect to PSTN.
However, AAR will not detect IP link failure.

Then let's asume that the directory number is diferent from the MSN. Who will tell the phone in a remote location what number to dial instead of the directory number?

 

[pndscm]

You are correct, I was wrong.

To do what you want to do, you will have to upgrade. In CCM 4.2 and above a field was added under the Directory number Call Forward page for Call Forward Not Registered. You would need to put in all the digits necessary to dial the remote number and the appropriate CSS. On the remote end, you'll have to have SRST configured to re-route calls also.

 

[lynxul]

That is a good piece of information!

It's not clear to me how a remote phone that has lost IP connectivity to the CCM will be able to dial a directory number from another location.

Who takes care of forwarding when the CCM is offline?

 

[pndscm]

If a local phone (1234) is calling a remote phone (5678) and the WAN goes down, on the remote phones CFWD Not Registered you would need to put all the dialing information (9XXXXXX5678) assuming 9 is your outside access and the 5678 line is a DID number on the remote gateway, the CSS on this setting needs to be something with outside access. Then on the remote site, SRST needs to kick in and in the programming there, the gateway would also need to prepend the 1234 number with the correct digits to connect the call across the PSTN assuming that 1234 is a DID also. If only one or neither lines are DID, then you'd have to use the Main number and have the console operator transfer you to the correct extension.

The answer to your question is the SRST router at the remote.

 

[lynxul]

Again great input!

When configuring the CFWD I need to select the calling search space.
Problem is I need diferent calling search spaces depending on the person calling (HQ, Office1, Office2, etc.)

Let's assume HQ 000, Office1 111, Office2 222;
Office 2 goes down; then Office 2 calls Office 1.
CCM redirects the call to 99(111); problem is I can only select Office2_ISDN1 callig search space. I'm not sure how that would fit.

Many thanks.

 

[pndscm]

If Office1 111 was going to call Office2 222 through the PSTN, would the Office2_ISDN1 calling search space allow it to happen? Remember, when the WAN goes down it is really the CCM programming for Office1 111 phone is actually calling the Remote phone not the original calling party/phone. So the CSS on the non-registered phone will determine if the call actually will go to the PSTN, not the original calling phones CSS.