As we can see that OCS 2007 R2 is the most common topic in microsoft forum nower days, thought of writing this article to give you a brief idea on Office Communication Server.

Let me start up with a question …… What is OCS ?

The answer is simple, “OCS” stands for “Office Communications Server.” It’s the abbreviated name for Microsoft Office Communications Server 2007. The current version is OCS 2007 R2 (stands for “Revision 2,” naturally). OCS 2007 is the centerpiece of Microsoft’s unified communications strategy to bring together e-mail, instant messaging, presence, voice and video on to a single platform.

It is a Session Initiation Protocol (SIP)-based server that routes and switches IP-based voice traffic, as well as instant messaging and Web conferencing sessions.

OCS is available in 2 editions :
1> OCS 2007 Standard Edition
Function :  IM/Presence, Conferencing, Voice
Purpose : All in one functionality for simple Deployment
Size : For Organisations with less or around 5000 users depend on load
We dont have High Availabilty

2> OCS 2007 Enterprise Edition
Function :  IM/Presence, Conferencing, Voice
Purpose : Higly avilable and scalable and suitable for big enterprise deployment.
Size : For Organisations with 125,000 users
High Availabilty :  Yes using Load Balancers and Multiple Servers in a Pool.

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Previous Versions
* 2009 – Office Communications Server 2007 R2
* 2007 – Office Communications Server 2007
* 2006 – Live Communications Server 2005 with SP1
* 2005 – Live Communications Server 2005, codenamed Vienna
* 2003 – Live Communications Server 2003

Possible Future Versions
* 2010 – Office Communications Server 2010 also named Wave 14

OCS 2007 Standard Edition

- Ideal for Branch Office or New Pilot Office
- It only require a single Server to manage all the funtionality of Instant Messaging, Presence, Peer-to-peerVoice, Conferencing.
- It is ideal solution for 5000 Users or less.
- Bundled up with Microsoft SQL Server 2005 Express SP2 (SP3)

OCS 2007 Enterprise Edition
- Command line Only setup.
Client Access Licensing  :
A CAL is required for each user or device (depending on the license) accessing the server. Either version of the CAL may be run against either version of the server.

The following usage scenarios for Office Communications Server 2007 R2 will require that CAL licenses be in place for each user or device:
• For Office Communications Server 2007 R2 voice extensions
• For internal users organizing or attending a Web conference
• For IM identities hosted on the Office Communications Server 2007 R2 Server

The following usage scenarios for Office Communications Server 2007 R2 will NOT require that CAL licenses be in place for each user or device:
• For users receiving a call from an extension hosted on the Office Communications Server 2007 R2 Server
• For Non Office Communications Server 2007 R2 users placing a call to an extension hosted on the Office Communications Server 2007 R2 Server
• For public network or federated users with an Office Communications Server 2007 R2 user
• For external users attending a Web conference

Microsoft Pricing for OCS 2007 R2

Software Requirements

1. Operating System  – X64 Only
2. Windows Server 2003 X64 SP2
3. Windows Server 2008 X64
4. Microsoft SQL Server 2005 SP2 or SP3 and SQL Server 2008
5. Active Directory Forest/Domain Level
   • Windows Server 2003 and windows server 2008 suppored.
   • - Exchange Unified Messaging : E2k7 SP1 or Exchange server 2010.

Hardware Requirement (Enterprise Edition)

1. Frontend Server

• x64 Dual Quad Core CPU, or 4 Way Dual Core CPU
• 8 GB Memory
• 10K rpm Disk Drives

2. Backend SQL Server

• x64 Dual Quad Core CPU, or 4 Way Dual Core CPU
• 16 GB Memory10K or 15k rpm Disk Drives (multiple Spindles)

3. Other Servers

• Use Frontend or Backend specification as appropriate

Difference between Ocs 2007 and OCS 2007 R2

• x64 bit Capable hardware required.
• x64 bit Operating System required.
• Migration Options
  - Side by side migration
  - Export data – New Install option

• Existing expanded topology deployment may want to migrate to consolidate topology
• Exchange 2007 SP1 required for Exchange Unified Messaging
• Deployments on Windows 2000 AD forest/domain to move to Windows 2003 minimum level.