Dial Plan in CUCM 9.1

[adamgibs7]

Hello
 

SITE-A DID

24247XXX till 24247999

SITE-B DID

222291XX  till 22229399

SITE-C DID

232361XX-23236299

Planning a IP telephony deployment with multiple site, site A and site B, site C, Calling between the site will be by access code, "7" for site A and "8"for site B and "5" for Site C,Also the PSTN access code is "9". IT manager wants to use 3 digit extension plan in all site which will overlap with other site.

what issues i will face in overlap extension and also highlight the issues with above design.

Thanks

[Jaime Valencia · Accepted solution]

You'll face no issue as long as you keep your CSS and partitions with only the calling privileges at each site as they need to. Then the TPs required to reach other sites. I don't see a reason why to use a separate digit for each site, you're just wasting numbering space. You usually see something like 8 + XXX + XXX

8 for inter-site dialing + 3 digit site code + DN

Have you explained your IT manager what a TERRIBLE idea is to use 3 digits, when you could overcome all this using 4??? Or a full E.164 dial plan??

Specially if this is a new deployment, seriously BAD idea.

I would suggest you, and your IT manager, to reach a partner to assist with this.

[adamgibs7]

Hello Jaime,

8 for inter-site dialing + 3 digit site code + DN

country doesn't have any long distance code so that's the reason i have not added the site code, and the IT manager is saying by dialing  8+ site code + DN it doesn't look like a  dialing a internal corporate DN but instead a PSTN number so he is saying me make it simple and short.

Have you explained your IT manager what a TERRIBLE idea is to use 3 digits, when you could overcome all this using 4??? Or a full E.164 dial plan??

Dear Jaime as an CSC expert i am not able to make him understand can you please list me the drawback and obstructions will be seen in future with the type of setup which my manager is proposing

Thanks

[Jaime Valencia]

TP = Translation Pattern

Simple: 3 digits overlap, 4 digits NO overlap

Which is simpler to configure, deploy, troubleshoot???

There is no rule to tell what an internal corporate DN should look like, you can get them in full E.164 and anywhere from 10 digits, to 3 digits. There is no hard rule. What you would see in most deployments, is that exact format, a digit for intersite dialing + site code + DN.

You need to get someone knowledgeable to look into this, see all the future growth, potential problems, other integrations, PSTN access, whether they're DIDs or not, etc

If you already have 990 employees at one site, do you think a 3 digit dial plan will do?? Where's the room for growth??, etc

There are far too many concerns and this is something someone needs to sit down with the company IT department to discuss with, and see the whole layout, if you lack the knowledge to do this, get in touch with a partner who has solid experience with this.

[adamgibs7]

Dear jaime,

As an expert, i am asking hints from you for the below line.

see all the future growth, potential problems, other integrations, PSTN access, whether they're DIDs or not, etc

what potential problems ??

what will be the issues with PSTN access ??

whether they are DID's or not ??? what can be??

I am asking you becz company  doesn't want to pay more for the partner so my manager and me are planning for best practice design.

ur help will appreciated.

Thanks

[Ayodeji Okanlawon]

Well if you do not have money to engage a cisco partner, then I suggest you take the free and excellent advise you are getting here. I am going to say it as it is..

Your manager doesnt know what he is talking about. Simple as that. 3 digit dialling doesnt scale. You have to think long term! what happens in the next 5 years, the compnay grows exponentially, you will quickly run out of DN.

As mentioned earlier, there is the potential for overlaps with just 3 digit dialling. So please listen now before you put in place a solution that will need to be redesigned and you will spend lots of money you dont have to get a reputable cisco partner to come and help..

Use the idea jamie has given you (and its free)

8+XXX+YYYY

8=inter site dial code

XXX=3 digit site code

YYYY= 4 digit extensions.

4 digit extensions alone gives you 10,000 numbers as compared to 3 digits which gives 1000 numbers..

Using a site code eliminates any possibility of overlaps even if your users extensions are the same, the site code ensures they remian unique..

example if you have a user in SITE A eith a DDI of 02070085112 and a user in SITE B with a DDI of 01180095112...

The users extension in cucm (using only 4 digits) will be the same 5112..however with a site code (say site a=712 and sibe b=715) Their extensions becone 7125112 and 7155112..You have eliminated the potential for an overlap and each users extension is unique..

You can use site specific xlaton patterns to make users use 4 digit internal dialling rather than dialling the full 7 digit numbers. Such that a call within the same site will be done using only 4 digits (thats not too hard for users) However any inter-site calls will have to use the full 8 digit number.

This is the best practice and like I said before its FREE! advise..So I suggest you take it!