I need help in designing a Dial plan that will fit our growing VOIP network.
We have a very large organization spread across the globe. Office size varies from 10 people to 500 +
We have call manager 5.13 deployed in NA with UNified messaging. We currently have 7 sites deployed with Cisco MGCP gateways with PRI lines. We have one CME deployed in South America (H323) and will be deplying another Call manager cluster in Europe with Unified Messaging. We have also just integrated an Avaya G3 V11 Definity with CCM using H323. I had to use a site code for the Avaya in London because of over lap on the existing Dial Plan.
So now that you know the lay of the land.
1) Currently we have 4 digit dial plan that is starting to overlap.
2) 2 digit site code is not good enough(too many offices)
3) 3 digit is too long (end user will not like it)
I like site code becuse I don't have to worry about what DID are availble from the Telco and overlap
It was suggested that 5 digit dialing would solve the problem.
I look forward to your collective wisdom or point me to good docuement where someone has implemented such a plan