On a client computer that is running Office Communicator 2007, you may be unable to make a TAPI call from Outlook 2007 or Outlook 2010
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Consider the following scenario:
On a client computer, you are running Outlook 2007 or Outlook 2010 and Office Communicator 2007.
You have registered a third-party TAPI Service Provider on the client computer.
In this scenario, when you try to use the Call feature for a contact in Outlook 2007 or Outlook 2010, the Office Communicator 2007 opens a voice conversation window unexpectedly and tries to dial the call instead of the registered third-party dialer.
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 How to back up and restore the registry in Windows
To make a TAPI call from Outlook 2007 on a client computer that is running Office Communicator 2007, install hotfix rollup 959642, and then set the TAPIOVERRIDE registry entry to enable the hotfix.
Install hotfix rollup 959642.For more information, click the following article number to view the article in the Microsoft Knowledge Base:
959642 Description of the Outlook 2007 hotfix package (Mso.msp,Outlook.msp): December 16, 2008
Set the TAPIOVERRIDE registry entry to enable the hotfix.
Start Registry Editor.
In Windows Vista or Windows 7, click Start, type regedit in the Start Search box, and then press ENTER.
If you are prompted for an administrator password or for confirmation, type the password, or provide confirmation.
In Windows XP, click Start, click Run, type regedit in the Open box, and then click OK.
Locate and then click the following registry subkey: