Calls from Communications Server 2007 Mediation Server may not be handled correctly when Mediation Server interacts with non-RFC 3966-compliant PBXs

By default, Microsoft Office Communications Server 2007 Mediation Server uses a plus sign (+) to prefix E.164 numbers in the Request Uniform Resource Identifier (URI) for outgoing calls. However, certain private branch exchanges (PBXs) do not comply with Request for Comments (RFC) 3966, “The tel URI for Telephone Numbers” and do not accept numbers that are prefixed with a plus sign (+). Therefore, an outgoing call may not be routed correctly. Additionally, the "From" headers for incoming calls from certain PBXs also do not comply with RFC 3966. In this case, Office Communicator does not resolve the number to the correct user.

To resolve this issue, follow these steps:

1. Install the update package for Communications Server 2007 Mediation Server that is dated August 2008. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
   952780  (http://support.microsoft.com/kb/952780/ ) Description of the update package for Communications Server 2007 Mediation Server: August 2008
2. Install the update package for Communications Server 2007 that is dated August 2008 on computers that have the following roles:
   • Standard Edition Server
   • Enterprise Edition Server – Front End
   • Proxy Server
   • Director Server
   • Edge Server
   • Forwarding Proxy
   For more information, click the following article number to view the article in the Microsoft Knowledge Base:
   952783  (http://support.microsoft.com/kb/952783/ ) Description of the update package for Communications Server 2007: August 2008
3. Install the update for Communicator 2007 that is dated October 24, 2008 on Communicator 2007 clients. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
   957707  (http://support.microsoft.com/kb/957707/ ) Description of the update for Communicator 2007: October 24, 2008

To make sure that Mediation Server operates correctly with non-RFC 3966-compliant PBXs, update 952780 adds a new Mediation Server configuration file setting for Communications Server 2007. This configuration file setting is called RemovePlusFromRequestURI, and it contains one of two values, Yes or No. If your PBX does not accept numbers that are prefixed by using a plus sign (+), the setting in the configuration file (MediationServerSvc.exe.config) should be Yes. The Yes setting causes Mediation Server to remove the plus sign (+) from a Request URI for outgoing calls. It also removes the plus sign (+) from the "To" header and the "From" header. If the configuration file setting is set to No, Mediation Server will not change the Request URI, the "To" header, or the "From" header.

If the MediationServerSvc.exe.config file does not already exist, put it in the directory that holds the Mediation Server software. To find this directory, search for the Microsoft.RTC.MediationServerCore.dll file, and then place the MediationServerSvc.exe.config file in the same directory.

Note For a default installation on the C drive, the Mediation Server software is located in the following directory: If the MediationServerSvc.exe.config file has a setting to strip the plus sign (+), its contents would be as follows: If the file does not exist or if it exists but has no setting for “RemovePlusFromRequestURI," the default setting for "RemovePlusFromRequestURI" is No.

Note This configuration file is also used to turn Transport Layer Security (TLS) on or off in the Mediation Server existing functionality. Therefore, the file may already exist on a particular Mediation Server computer. By default, if the file does not exist or does not have the GatewayTLS setting, TLS is turned off.

The contents of the file are as follows when the file is used both to strip the plus sign (+) and to enable TLS: Note The Mediation Server must be restarted for changes in the configuration file to take effect.

Update 952783 introduces functionality for Communications Server 2007 to normalize the "From" header so that a non-RFC 3966 representation of an E.164 number is converted to an RFC 3966 representation and is placed in the P-Asserted-Identity (PAI) header field. If normalization does not result in an E.164 number, Communications Server 2007 includes a phone-context value of "enterprise” in the PAI header. The PAI header enables the user lookup functionality in Communicator 2007. Additionally, Communications Server 2007 bypasses the server normalization logic if the Request URI header contains a phone-context value of "enterprise."