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VoIP Dial Plan Conversion from 4 digits to 5 or 6 digits

yogesh bhalerao
Level 1
Level 1

Hi Team

I am exhausting my current 4 digit VoIP dial plans and soon need to implement New VoIP dial plan keeping in mind the existing dial pattern 

My DID numbers are different then my VoIP numbers e.g 6666 9202 and voip :- 1202


 Currently i am thinking of changing the 4 digits to 6 digits so that i can increase the numbers and the digits 


Can anybody suggest how to go about it ?




Can anybody suggest how to go about it ?

12 Replies 12


Details will depend on which call platform you're using, CUCM, CME or something else.  However in general what you'll need to do is change the directory numbers, change any translation patterns or rules that convert incoming dialed numbers into your extension numbers.  You may also have to change voicemail mailbox IDs, rules for external number display, directory entries etc. 

Hi Tony

Thanks for your reply 


Actually i am using CUCM, also i have SIP trunk with locations EPABX , mine the VoIP extensions and DID numbers are different 


e.g. 6666 9299 DID 

       1299 :- VoIP 


OK.   The directory numbers can be changed in place with a downloadable third party tool.   The one I've used was called "Netpacket Renumber DNs.exe" and just used a text file with old number and partition, new number (optionally new partition).  But you also have to look at inbound and outbound call handling. 

Do you use translation patterns to map incoming calls onto the DNs? 

If you're renumbering anyway it might be a good time to consider E164, or at least to change to a better match with external number (for example make your new DN 669299 for external number 66669299.

Really there's any number of ways to do this depending on your wider requirements.  Before jumping into anything test everything with one manually edited number.

Hi Tony

There is SIP trunk between CUCM and my EPABX 

EPABX is doing the translation of DID with VoIP extns. in CUCM we create dial pattern 

The point here is i am checking one location as test case whose series is from 1000-1999 and even if i convert the 4 digits with 6 digits(below e.g.)  will this change help me in increasing the extension count and will this work 



Change to 11 1000 - 11 1999 

So your options are either to change the EPABX (whatever that is) to convert into six digit extensions, or you could convert on CUCM.   How many digits are presented on the trunk from the EPABX?   Does it's CSS reach the DNs directly, or via a translation pattern.  If you could explain your current dial plan and call handling in full it's easier to make specific suggestions.

Hi Tony

The translation is done by EPABX for DID to VoIP and it sends 4 digits from EPABX to CUCM 

The CSS reaches the DN directly 

The current dial plan is of 4 digits between the locations 

Hope i answered your queries 


So for incoming calls you could leave the EPABX as four digits and use a translation pattern in CUCM to expand to your new six digit pattern.

When you say "four digits between the locations" do you mean you have four digit numbering at each site, and you're now finding that you can't expand without finding conflicts?   What overall new scheme do you have in mind?

Yes we are having 4 digit VoIP dialing Plan between the locations and now we are exhausting the dial plan and finding it difficult to expand for the new VoIP series 


dial plan :- 10XX, 12XX,13XX,14XX,15XX,16XX,17XX,18XX,19XX, 20XX, 21XX ....... 99XX 


So this is the dial plan it starts with 10XX and goes on till 2,3,4,5,6,7,8,9 series till 99XX and now all the numbering series are exhausted and want to expand the series without changing the series but adding the new numbers and making it 6 digit so that would get more numbers  

Couple more basic questions. How many sites do you need to plan for? Are you going to renumber all sites in one go, or do you need to co-exist renumbered sites with four digit sites? Do you need to retain four digit dialing within each site, only dialing 6 digit to call elsewhere?

Hi TOny

I am planing more than 20 sites and i want to retain my 4 digit numbers and add 2 more numbers to increase the digit count to 6 so that my numbers at each site would increase 

OK provisionally two digits is plenty for 20 sites, assuming you don't want numbers starting 0 or 9.  The reason I asked about internal 4 digit dialing is that it would introduce a further limit.  Take for example a site currently number 25XX and renumbered to 1125XX.  If you wanted them to still be able to call each other as 25XX then that would mean you couldn't have a full six digit number starting 25.

No i want to keep the existing dial pattern with addition of 2 more digits so that i get more numbers 


e.g. 25XX change to 1125XX so in short user will have to dial 6 digits for VoIP but i need to add the extra 2 digits in such a way that the existing numbers would be retain and with addition of 2 numbers i can increase my VoIP numbers to more quantity at sites 


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