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Configure Lync 4 Digit Extension Dialing without DIDs

Project Scope
Preparing for Deployment – Research and Education and Pricing
Deployment of Standard Server & Director Role
Deployment of Edge and Reverse Proxy
Deployment of Lync Voice Capabilities
Configuring Lync PSTN Calling thru Avaya IPOffice
Configure Lync 4 Digit Extension Dialing without DIDs
Configure Asterisk as a SIP Proxy for Avaya IPO and and Lync
Deployment of Lync Client to users
Testing Configuration of Backup Registrar


This post isn’t in the planned sequence of documenting the Lync Deployment in this series, but I found the topic fairly frustrating and undocumented today so I decided to go ahead and post this now.  Our primary location has DIDs for each extension, but or second campus only has a few POTs (Plain Old Telephone) lines for service so there are not DIDs for each extension.

Lync Extensions without the use of DIDs (Direct Inward Dial)
When deploying Lync Enterprise Voice each user is configured with a SIP Address as well as a telephone Line URI.  In deployments where every extension has a DID the Tel URI can simply be the external DID number associated with that user.

When you make a 4 digit extension call internally, Lync uses your defined Dialing Rules and normalizes the number to the E.164 format.  When dialing extension 5555 Lync would normalize (because you configured this normalization rule already) it to: +112355555555 for a US telephone number of (123) 555-5555 and will route the calls internally to the appropriate user.  Since the call matches a Lync user the call isn’t routed to the PSTN (Public Switched Telephone Network).


When a user doesn’t have a DID, you can also enter a user’s Tel URI with the extension added  in the following format: +112355555555;ext=1234 where the main telephone number is (123)555-5555 and the extension is 1234.


Even though you have created the user with the main number and extension you won’t be able to make 4 digit calls without adding additional dialing rules so the call can be completed.

To make calls to 4 digit extensions that do not have DIDs go to Lync Server Control Pannel > Voice Routing and select the appropriate Dial Plan. Once you are viewing the appropriate dial plan choose new “Associated Normalization Rule”.  Give the new Rule a Name and Description. Then skip all the boxes for Starting Digits, Length, Digits to Remove and Digits to add and go to Pattern To match and select Edit.



This example will allow dialing for 4 digit extensions starting with 12## associated with the main number (123) 555-5555
(extensions 1200-1299)
The Value for “Match this Pattern” is: ^(12d{2})$
The Translation Rule is: +11235555555;ext=$1

Rule Expression

After you save and Commit the Rules and they replicate to your Lync Clients you will now be able to dial 4 digit extensions that don’t have a DID.



  • Reply Jim B |


    i was able to make this work for the translation, however instead of keeping the call inside lync, it is actually routing to my gateway (in this case asterisk) since asterisk does not know what do do with that number, it hangs up. What do I need to do to allow the 4 digits to stay internal to lync?

    • Reply jasonlee |

      @Jim B. do your extensions have the tel:+00000000000;ext=1234 if you don’t have that value then then lync thinks the extension is outside and routes the calls in your case to the asterisk.

    • Reply jasonlee |

      @Anthony B. Have you created a normalization rule to translate dialing 4 digits to the E.164 format?

  • Reply Jose Maria Gonzalez |


    Lync can use the symbol “number” # in the dial plan? Example must call extension ##4698, I set the path to the dial plan to rule ^(##(d{4}))$ also ^(##(d{4}))$ and change the # to %23 generating an error in the call. The Lync test to verify the normalization runs successfully, but when marking the gateway generates error that marks %23%234698 instead of dialing ##4698.


  • Reply Richard |

    Hello Jason,
    Nice article. And it seems that you might be the person to help me resolve this issue I have been facing.
    I cannot dial Lync extensions that are already configured by Lync extensions .
    So Joe number is +15149011123;ext=1234.
    When I dial from bob whose number is
    I get error 485 multiple numbers associated with source phone number.
    I have checked and determined that we don’t have the main number without an extensions. However I can dial from any phone number without a link extension so phone 655 can dial Joe and bob.
    I need help creating a rule that will remove the main number from Lync extensions so that I don’t get the dreaded 485 error

    • Reply Jason Lee |

      @Richard are you diailing joes’ 4 digit number from bob’s lync client or phone? Are you normalizing 1234? I don’t know that you want to remove the main number and just leave the extension. I would have to know a little more about your dial plan. Could you post your dial plan rule or email it to me?

      • Reply Richard |

        Hi Jason,
        Sorry for not getting back to you.
        I was able to resolve the Issue by removing the (+) sign.

  • Reply Louis Laan |

    We have around 150 dial plan’s (each for every office). 20 of them are a Lync only office. In each of those 20 dial plan we can put in a normalization rule where we can change the 6 digit internal number into their E164 number so it is possible to dial 6 digit wise within their own office. I would like to know if it is possible to have those 20 6 digit ranges being dialable form every other Lync phone(office, Dial Plan).

So, what do you think ?