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Posts tagged with: Enterprise Voice

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.