You must have:

• Deployed Microsoft Exchange Server 2010 in your organization.
  
• A working Communications Server 2007 R2 environment.
  
• A certificate that's trusted by the Communications Server 2007 server and the Client Access server and is issued by the same authority.
  
• A certificate that has the Client Access server namespace as the subject on the Subject line. The namespace may be the name of a particular Client Access server, or it may be a DNS name that's used for load balancing across multiple Client Access servers.
  
• The Client Access server namespace must be in the Communications Server 2007 trusted hosts list.
  
• The fully qualified domain name (FQDN) of the Communications Server 2007 server or the Communications Server 2007 pool.
  
• Enabled your users to use Communications Server 2007 via the Communications Server 2007 user administration tools.
  

You need to be assigned permissions before you can perform this procedure. To see what permissions you need, see the "Outlook Web App virtual directories" entry in the Client Access Permissions topic.

1. On the Client Access server running Windows Server 2008 or a later version, download and install UCMA 2.0 from Unified Communications Managed API 2.0, Core Runtime (64-bit).
   

   Note:
   UCMA must be version 6907.210 or a later version. If you have installed a previous version of UCMA, you should uninstall it before you install the later version.

2. On the Client Access server, download and extract the CWAOWASSPMain.msi file from: Microsoft Office Communications Server 2007 R2 Web Service Provider.
   
   1. The following files are extracted to the Web Service Provider installer package location:
      CWAOWAASSP.msi
      Donnetfx35setup.exe
      UcamRedist.msi
      Vcredist_x64.exe
      
3. Double-click CWAOWASSP.msi to install the Microsoft Office Communications Server 2007 R2 Web Service Provider.
   
4. Download and install the hotfix from OCS 2007 R2 Web Service Provider Hotfix version 6907.202.
   

Use the following checklist to make sure that the installation was successful:

• Look for the InstantMessaging key in the registry under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchange OWA\. The string under InstantMessaging with the name ImplementationDLLPath and the value "<Your Exchange Install Path>\ClientAccess\owa\bin\Microsoft.Rtc.UCWeb.dll" should have been created.
  
• The Microsoft.Rtc.UCWeb.dll file should be present in the directory <install drive>\Program Files\Microsoft\Exchange Server\V14\ClientAccess\Owa\Bin.
  
• The files SIPEPS.dll and Microsoft.Rtc.Collaboration.dll should be present in the Microsoft .NET Framework Global Assembly Cache.
  

You need to be assigned permissions before you can perform this procedure. To see what permissions you need, see the "Certificate management" entry in the Exchange and Shell Infrastructure Permissions topic.

The Client Access server must be configured to use a certificate that's trusted by Communications Server 2007.

Note:
The certificate on the Client Access server and the Communications Server 2007 server must be from the same issuer.

Note:
If all your Client Access servers are in the same namespace, you can use a single certificate for all of them.

After the certificate is in place on the Client Access server, use the Exchange Management Shell to get the certificate information by running the following command on the Client Access server.

get-ExchangeCertificate | fl

Locate the certificate you want to use, and then record the thumbprint.

When you configure the Communications Server 2007 host authorization list, you'll add the certificate subject as the name of an authorized host.

For information about how to obtain and configure a certificate for a Client Access server, see Obtain a Server Certificate from a Certification Authority.

Select the same Communications Server 2007 pool you used for the next hop server for Microsoft Office Communicator Web Access server. This server will proxy all SIP requests to the destination pool. For more information about the next hop server, see Creating a Communicator Web Access Virtual Server.

You need to be assigned permissions before you can perform this procedure. To see what permissions you need, see the "Outlook Web App virtual directories" entry in the Client Access Permissions topic.

This example configures which Communications Server 2007 pool to connect to, the certificate to be used, and enables the Client Access server to use Communications Server 2007 for instant messaging.

Get-OwaVirtualDirectory | Set-OwaVirtualDirectory -InstantMessagingServerName <name of Instant Messaging server or pool to connect to> -InstantMessagingCertificateThumbprint <certificate thumbprint> -InstantMessagingEnabled true -InstantMessagingType 1

Note:
You may have to restart Internet Information Services (IIS). You can do this by opening a Command Prompt window and using the iisreset/noforce command.

For detailed syntax and parameter information, see Set-OwaVirtualDirectory.

For information about how to configure Communications Server 2007 to work with Outlook Web App, see Administering Web Service Provider in the Communications Server 2007 documentation.

After you enable Communications Server 2007 integration on the Client Access server, you may also want to use segmentation or Outlook Web App mailbox policies to enable or disable IM for users.

• Managing Outlook Web App Mailbox Policies
  
• Set-CASMailbox