I have moved into a new position at a global company and need to catch up on best practices for configuring international dial plans. I believe that I want to globalize numbers coming inbound using plus dialling. However I haven’t been able to find the documentation on how to set this up. Can someone point me in the right direction?
Cisco's international dial plan approach in 7.x is pretty straight forward. At least conceptually. The idea is that the CUCM will accept digits that are dialed or sent using the format that is native to the sender. So, for an IP phone user on your cluster this may be offnet access code (e.g. "9") followed by digits appropriate for the geographic area. For example, in Washington, D.C. a user can dial local numbers as 9 + 7-digits (NXX-HHHH) or 9 + 10-digits (NPA-NXX-HHHH). Long distance would be 91 + 10-digits (1-NPA-NXX-HHHH). On the flipside, the carrier switch will hand off calls in a specific way. This is actually negotiated between the customer and the carrier. Some people lack foresight and order DIDs that match their abbreviated dialing extensions. Some people order DID lengths that match the geographic dialing rules. Some people order DID lengths that are "fully qualified". At least, this is true for NANP.
Now, the CUCM will accept digits in the "local" format. Next it will "globalize" the digit string. So, in vanilla terms this means use the e.164 format (i.e. plus "+" dialing). So, a number in Washington, DC may be 2025551212. In e.164 format it is +12025551212. The CUCM digit analysis will then be applied to the fully qualified e.164 number. If a destination is found, the call is routed. Last step is how the digits are presented to the destination station or voice gateway. Again, CUCM will "localize" the digit string to what the user is used to seeing/dialing/etc. or what the carrier switch can process. Using the last destination as an example. In the US, most class 5 switches don't know how to handle a "+" in the digit string so, you have to dumb it down to what the switch can handle (e.g. "1" + 10 for LD, "011" + country code + digitstring for international, etc.).
Digits Received --> Digits Globalized --> Routing Decision Made --> Digits Localized and call delivered
I recommend that you start with the Cisco Unified Communications SRND based on CUCM 7.x:
You could also use the SRND based on CUCM 8.x if that is more applicable.
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