Microsoft Arrives at UC Destination

By Andrew Garcia  |  Posted 2008-02-06

Microsoft Arrives at UC Destination

Microsoft has been seemingly inching toward unified communications for years, but with Office Communications Server 2007, the company is finally there.

By integrating VOIP (voice over IP), videoconferencing and instant messaging in a single slick and with a familiar user interface-while layering on unified mailbox and collaborative work sessions-Microsoft has put together a compelling communications and collaboration solution, particularly for companies that are already heavy users of Microsoft infrastructure components.

For users at such organizations, the UC tools could not be much more familiar. OCS 2007 bakes real-time presence information into Office (Versions 2007 or 2003) and Office Communicator 2007, allowing users to trigger communication sessions directly from their contact lists, e-mail messages, shared documents and more.

OCS 2007 also allows users to easily navigate among communication modalities, with the ability to view other users' status across the enterprise to gauge the most effective communication mode.

Click here for screen shots of Office Communications Server 2007. 

For example, User A may see that User B is marked "Away," so User A sends an e-mail to User B instead of an IM. User B returns and sees that User A is present. User B responds to User A's e-mail with an IM, at which time User A upgrades to a voice or video call with User B. Each conversion takes only a click or two per user. Likewise, callers can upgrade a two-party call to a full-fledged conference with a minimum of clicks, and new parties will get invited automatically via e-mail.

Once in conference, the system has the intelligence to put the focus where it needs to be. For instance, in a videoconference, the video image represents the person actually speaking at the time, and it will shift as the conversation moves from person to person. In addition, conference participants can share documents or applications, and the conference lead can pass application control to other parties as needed.

All this experience is meant to occur directly from the PC, with no need for a desktop phone at all. I tested OCS 2007 using a variety of off-the-shelf Webcams and USB headsets, but Microsoft also provideda few accessories designed specifically for use with OCS: a USB handset called the Catalina and the Polycom Communicator C100 personal speakerphone, both of which provide minimal controls to pick up or drop calls from the respective device itself. Still, the lion's share of control is performed on the desktop.

Exchange Server 2007, which provides unified mailbox capabilities, is required by OCS on the back end. Users can access all their messages from one location now, with the ability to listen to voicemails directly from the computer (no punching codes into the phone) and return a call directly from the message itself. Exchange Server 2007 also can archive Office Communicator chat sessions.

OCS allows users to check in from PCs that do not have Office 2007 installed via the OCS Communicator Web Access server role. Users log into a Web server to gain access to a Web-based Communicator, which provides the ability to search for users throughout the organization. While users cannot make VOIP calls through this interface, they can initiate IM sessions with other users and forward incoming calls from their office extension to a convenient telephone number (such as a cell phone).

OCS 2007 is licensed in both Standard and Enterprise editions. The Enterprise edition is for companies looking for high-availability clustering and costs $2,790, plus $698 for one year of Software Assurance. Standard OCS licenses run $488, plus $122 for one year of Software Assurance. The real costs will likely start adding up when you add in the Office Communications Server CALs (client access licenses) and External Connector Licenses that will need to be purchased for users participating in audio, video or Web conferences. (Note: Prices do not include the costs for Exchange Server, Office or SQL Server.)




At first glance, OCS seems daunting to install, but many of the required components are likely already in existence in corporate networks.

You'll need an Active Directory server, hosting core network services (such as DNS), and a Certificate Services server. You also need Exchange Server 2007 configured with the Unified Mailbox role, plus SharePoint Server and SQL Server.

The OCS 2007-specific components include the primary OCS system (including an A/V MCU), a Mediation Server that transcodes outbound calls destined for the PSTN (Public Switched Telephone Network) (I used an AudioCodes MP-114 Analog Gateway), a Communicator Web Access Server and a Quality of Experience Monitoring Server (more on that below). Both the primary OCS system and the Quality of Experience servers require SQL Server on the back end.

Microsoft provides copious amounts of literature to help organizations right-size their OCS deployment. In general, most OCS components in a geographically distributed network could be hosted centrally. However, Microsoft representatives definitely recommend the Mediation Servers be distributed to where the trunks are located, and they also suggest distributing A/V MCU servers to aid in multiparty calls.

However, I'd recommend at least talking to qualified third-party resources as a sanity check before going too far with OCS deployment plans, to ensure the project meets both current and future performance requirements.



Microsoft currently supports two avenues of integration with SIP- (Session Initial Protocol) based equipment.

PSTN gateway devices bridge calls between the SIP-based telephony network and the analog PSTN. In addition to the AudioCodes equipment I tested with, OCS can work with PSTN gateways from Cisco Systems, Dialogic, Network Equipment Technologies and Quintum Technologies.

 OCS also integrates with certain IP PBXes. Enterprise customers that are not ready to perform a forklift replacement of existing telecom equipment in favor of OCS-either because the existing system has not reached end of life or because OCS does not provide all the enterprise telephony features expected from a voice system-may want to investigate OCS' PBX integrations to marry OCS' desktop functionality with existing desktop phones and backed systems.

 At this time, Nortel Networks is the only third-party PBX vendor qualified to work with OCS. However, the integration happens via SIP, so other solutions may work to some extent.

As I saw in person at Nortel Networks' facility in San Ramon, Calif., a Nortel CS1000 PBX-running the most up-to-date code-supports dual forking with remote call control. This means that a Nortel phone and an OCS Communicator session can share a twinned extension-one that rings through in both places, allowing a user to seamlessly move from one device to the next, with OCS' presence capabilities being aware of activity on the PBX extension.

Quality Control


Quality Control

Because OCS voice and video calls are encrypted by default, network administrators will only be able to glean a limited amount of QOS (quality of service) information from standard network-based VOIP monitoring tools. To overcome this shortcoming, Microsoft produced the OCS Quality of Experience Monitoring Server role to help administrators monitor ongoing network experience with insight gleaned from within the system.

Instead of viewing packets strictly from a network perspective, the Monitoring Server aggregates data from the primary call control servers (which cull data from the endpoints) and from the Mediation Servers (to monitor calls to and from the PSTN). This data is collected in the Monitoring Servers' SQL Server database, which can be queried using prepackaged Web-based reports.

The reports are broken out according to avenue (PC-to-PC calls, PSTN-to-PC calls, PC-to-PSTN calls, and conference calls) and provide several different MOS (mean opinion scores) to represent incoming and outgoing sound quality, among other assessments. The reports also provide information on metrics like codec used, packet loss, packet reorder, packet errors, jitter and even the end-point device in use.

Since OCS by default uses Microsoft's RTAudio codec-which operates as either a high-definition wideband or narrowband codec, depending on network conditions-all reported MOS are based on the richer experience expected from a wideband call. Therefore, an in-network call between two people on the same subnet may get the maximum MOS of 4.1 (using a wideband codec), while a call to the PSTN using a narrowband codec (as that's all the PSTN will support) will only get a score of about 2.5. Consequently, network administrators will need to be re-trained in the new scoring criteria applicable for high-definition audio.

Senior Analyst Andrew Garcia can be reached at

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