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Community Member

Dial plan design guides

I just came to a job where the existing dial plan is all in one partition basically. They have outgrown this and I am trying to come up with a new dial plan but am having trouble. Does anyone know where there is good dial plan documentation or design guides?

Hall of Fame Super Silver

Re: Dial plan design guides

Have you reviewed the CCM SRND doc?


Community Member

Re: Dial plan design guides


Yes I have reviewed the SRND doc and it is helpful, but we have a large IPCC ent right now.

There are 6 sites + 3 outsourcer sites. So the 1 partition thing is really a mess. 10,000 numbers almost all used up. I want to break the call center out but so far my designs seem clunky.

Basically following the "traditional approach" to CSS and parts. So generally for each site there are now 9 new CSS's /3lines /1 internal /1 pstn inbound /local /LD /International /Site CC Agents and a /VM only.

There is a global IPCC CSS with 3 parts. agents, icm, and ivr.

Moving from one partition to this is going to be really intense. It just seems like their has to be a more elegant way but I can't find any documentation other than the SRND doc and the "line/device" approach doesn't really fit :(

Hall of Fame Super Gold

Re: Dial plan design guides

If you can start from scratch, assuming it is a medium organization that you are talking about, I would propose a four digit (including site ID) numbering plan. Of course it can be expanded to five or more digits as needed.

Quite simply, main sites (assume 3 or less), use 1 digit site ID, all extensions are 3 digits. Other smaller sites uses 2 digits site ID, 2 digits extensions, but with only 80 numbers available. You can have 20 or 30 of these sites. Intersite dialing is done with a prefix digit, but if you decide that ALL internal calling must be 4 digits, you can use it for other purposes. In summary:


0 timeout - operator

0xxxx -> external call

1... -> reserved where used for emergency services - alternatively use 9 or none, as required.

2x - 8x -> insite call to ext, in sites using 2 digits ext. Also avail 1x or 9x.


2xx - 8xx -> insite call to ext, in sites using 2 digits ext. Also available, 1xx or 9xx.

(1, 9 or other digit)yxxx -> call to site y, 3 dgts ext.

(1, 9 or other digit)yyxx -> call to site yy, 2 dgts ext.

9 -> reserved where used for emergency services - alternatively use 1 as required.


as above, and because there is no intersite prefix, one additional digit (1 or 9) is made available to add another large site, or 99 smaller ones. Structured organization may see this better.

I hope all this make sense for the problem you are facing.

Community Member

Re: Dial plan design guides

This does help, but I need more space. 4 digits currently used but i may need to go to a 5 digit dial plan.

Also, I can't start from scratch:( There are over 600 cti route points and 600 cti route ports spread across the all of the ranges from 1xxx to 8xxx :( Plus over 1000 CC agents mixed in. If I can partition out the Call Center, then I would only need 3000 DID's for each of 6 main sites, plus there are 3 smaller vendor sites with less than 500 DID's needed.

Community Member

Re: Dial plan design guides


To increase th enumber of extensions you don't really have to increase the number of digits, You can re-use the same extensions. In all off your sites with a 4 Digit plan.

The method works like a multi tenant implementation.


Hall of Fame Super Silver

Re: Dial plan design guides

You should implement either site codes, which can be the 3 digits of your exchange number or dedicated 3 digit site codes, prefixed with an on-net access code such as 8. Or you can go with full 10 digit dialing between sites.

This way your environemnt becomes a lot more scalable, and you can have overlapping 4 digit DNs.

With this configurtation your phone extensions would be 8 or 11 digits (you would include the on-net prefix, or you may not but then you'll need additional transaltion patter), but at the same time allow 4 digit dialing intra-site, where a TP would prefix the appropriate site code.

You would still keep all of your phone DN in one parition.


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