TAPI Is Not Terminal Services Aware

Programs that control telephone systems through a serial interface (COM port) may not work when using Terminal Services.

Even though you can redirect a COM port to the client in the user session, a Telephony Application Programming Interface (TAPI) Telephone Service Provider (TSP) cannot access the COM port.

This problem occurs because TAPI and the TSPs run as services in Windows 2000 and TSPs cannot access COM ports that are mapped in a user session. Therefore, the services run in a different logon session than the user programs.

Redirected COM ports are mapped in the per-session object name space. For more information about this behavior, view the section about "Kernel Object Name Spaces" in the "Platform SDK: Terminal Services" Microsoft Developer Network (MSDN) chapter.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section of this article.

Because of the infrastructure in the TAPI architecture, a TSP cannot be Terminal Services aware. There is no existing way to implement a TSP that is Terminal Services aware.