Microsoft KB Archive/240863

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BUG: LINE_REPLY After a lineMakeCall Contains a dwCallbackInstance of 0 on Windows CE

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Q240863

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The information in this article applies to:


 * Microsoft Win32 Application Programming Interface (API), included with:
 * Microsoft Windows CE Operating System version 2.0

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SYMPTOMS
The LINE_REPLY message received in response to an asynchronous call to the lineMakeCall function always returns a dwCallbackInstance of 0 (zero) on Windows CE.

RESOLUTION
One possible workaround for this issue is to save the value of dwCallbackInstance in a global variable, to be used when the LINE_REPLY message is processed.

STATUS
Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article.

MORE INFORMATION
When calling the lineOpen Telephony application programming interface (TAPI) function, an application passes in a dwCallbackInstance, which should be returned to the application on subsequent asynchronous LINE_REPLY completion messages.

After calling lineMakeCall, a LINE_REPLY message is received by the application indicating that the lineMakeCall function successfully completed. The LINE_REPLY message includes a dwCallbackInstance, which should be set to the same value as the dwCallbackInstance originally passed in to the lineOpen call. On Windows CE, the dwCallbackInstance included with the LINE_REPLY message in response to lineMakeCall is set to zero.

You can store dwCallbackInstance in a global variable if you have only one line open. If, however, you are managing multiple open lines with different callback instance data, then you need to associate the proper dwCallbackInstance with the request identifier returned by lineMakeCall and contained in dwParam1 of the LINE_REPLY.

Additional query words:

Keywords : kbAPI kbKernBase kbTAPI kbOSWinCE200 kbDSupport kbGrpDSKernBase

Issue type : kbbug

Technology : kbAudDeveloper kbWin32sSearch kbWin32API