Microsoft KB Archive/323151

= New Unimodem comm/datamodem device classes =

Article ID: 323151

Article Last Modified on 11/21/2006

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APPLIES TO

 Microsoft Win32 Application Programming Interface, when used with:  Microsoft Windows 2000 Standard Edition

 Microsoft Windows XP Professional 

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This article was previously published under Q323151



SUMMARY
With Microsoft Windows 2000 and later versions of Windows, Unimodem separates the TAPI comm/datamodem device class into two separate device classes:
 * comm/datamodem/dialin
 * comm/datamodem/dialout

These new device classes can be used on any Unimodem device and in any API where a device class can be specified.

When used in the lineSetDevConfig function, each class sets the modem configuration for all telephone calls until the next call to the lineSetDevConfig function:
 * comm/datamodem/dialout for outbound calls
 * comm/datamodem/dialin for inbound calls



MORE INFORMATION
On versions of Windows earlier than Windows 2000, applications must configure TAPI modem devices for their own use, whether they make outbound or inbound calls. However, if one application, such as HyperTerminal, makes an outbound call while another application, such as remote access, waits for inbound calls, the outbound application might configure the device in a manner that is not compatible with the inbound application. The new device classes on Windows 2000 make this kind of conflict less likely.

Note These new device classes are not supported by any version of Unimodem earlier than Windows 2000. Also, they are not supported by many third-party technology solutions professionals. We recommend that applications first try either comm/datamodem/dialin or comm/datamodem/dialout. If these do not succeed, use comm/datamodem.

If an application uses comm/datamodem, this always uses comm/datamodem/dialout. However, this behavior is intended for earlier (legacy) applications. We recommend that developers use the new device classes to make their intentions clear.

