In many organizations, users have a mobile phone as their work phone and private phone. As an example, many companies in Norway have made the mobile phone number a user's primary phone number, and the user can be reached only on this number. Traditionally, operators have offered their customers net-centric logic for their call handling and switchboards and have used mobile phones as their only phone. Because users use the same phone at work and privately, they have only their mobile number, and the number follows the user and not the company.

When my team started deploying Microsoft Office Communications Server 2007 R2 for these companies, they wanted the solution to be built by using mobile phone numbers as the primary number when calling from Microsoft Office Communicator. As a result, operators in Norway, such as Telenor and Netcom, are offering IP trunks that integrate with Communications Server 2007 R2. By using these IP trunks, they can rewrite the caller's number from a PSTN number to a mobile phone number before the call reaches the PSTN network. This enables users to have a single mobile number. And when the called party calls back to the mobile phone number, the Communications Server PSTN number is called at the same time by using dual forking that is provided by the operator. However, when Exchange Unified Messaging (UM) is added to this scenario, issues arise. This article explains the problem and gives the solution.

Author: Ståle Hansen

Publication date: January 2011

Product version: Microsoft Office Communications Server 2007 R2, not verified for Microsoft Lync Server 2010

The Problem

If you add Exchange Unified Messaging (UM) to the mobile-phone-as-primary-number scenario described earlier in this article, you get an issue. The integration itself works fine and as expected. The problem occurs when the users log off their computers and go to meetings, drive home, or are generally not logged on. What happens is that when the user is not logged on to Communicator and someone calls, Communications Server answers the call in under a second. The user's call forwarding settings in Communicator are ignored, and the call is forwarded to Exchange UM. As a result, the user loses the call on the mobile phone. Exchange UM, therefore, breaks the solution. This is by design and my team has not been able to implement Exchange UM in the unified communications (UC) setting in these scenarios until now.

Using Exchange UM with Communications Server

If Exchange UM is causing some issues why is our team so eager to implement Exchange UM in these scenarios? When using the operator's net-centric voice mail features, some technology and integration is lost. For example, by default, users get a Short Messaging Service (SMS) message that tells them they have a new message, and they can call in and hear the message. Some users configure their voice mail so that it sends an e-mail with a .wav file of the message to their inbox. However, after listening to the .wav file in Outlook, the message is still "unheard" if the user calls the operator voice mail. There is no integration between the operator's voice mail and Exchange. That is why we want to have Exchange UM deployed to have a complete UC solution.

Exchange UM has several advantages, such as the following:

  • Integration with the Exchange inbox: Messages that are heard or read in Microsoft Office Outlook or Microsoft OutlookWeb App, oron a mobile phone using Exchange ActiveSync are also read when the user calls the Exchange UM service.
  • Call back functionality directly for Outlook Web App: Users can have Exchange UM call them and play the message on the phone of their choice.
  • Note field integrated in Outlook and Outlook Web App: This allows users to take notes in Outlook while listening to the message, and then saves and indexes the note.
  • Call-in access to the calendar: Users can call Exchange UM and rearrange their calendar, which is very handy when late for a meeting driving a car.

Read more about the Exchange UM server role.

The Solution

After about a year of research, I found a way to work around this issue that Exchange UM has with Communications Server by using Front End Server scripts and a program that puts the call on hold for a given period of time. I came across a Scandinavian developer company called Competella. They develop applications based on Unified Communications Managed API (UCMA) and are currently developing a switchboard attendant that integrates call control with an advanced directory search tool to enable access to presence, calendar, e-mail, and IM. The system adds attendant call control functionality to Communications Server beyond the level found in legacy PBXs. They developed a script and a program that checks the status of the user. If the user is offline, it will put the call on hold for 20 seconds before forwarding the call to Exchange UM. This solves the problem with users who use only a single mobile number. This also works if a user has their status set to "in a mobile call" by third-party programs that get free/busy information from the operators of a user's mobile phone.


By using the script and program from Competella we are able to complete our UC deployments with Exchange UM when a user's mobile phone is their primary and only number. With this we are able to implement enterprise voice mail for mobile phones as well as in Communications Server.

Additional Information

To learn more, check out the following:

Keywords: Exchange 2010 UM, OCS 2007 R2

Lync Server Resources

We Want to Hear from You