comm/datamodem/dialin

The comm/datamodem/dialin device class consists of datamodem devices used only for incoming calls. This class replaces the comm/datamodem class on Windows 2000 and later operating systems.

Before Windows 2000, the Unimodem TSP only supported the comm/datamodem device class. Unexpected behavior may occur when an application dialing an outbound call changes the configuration set by a service waiting for an incoming call. Applications using Windows 2000 and later operating systems should specify either comm/datamodem/dialin or comm/datamodem/dialout in calls to lineConfigDialog or lineSetDevConfig. This enables Unimodem to maintain a dial-in configuration independent of the dial-out configuration.

While comm/datamodem/dialin is used by Unimodem on Windows 2000 and later, it may also be used by other TSPs on any platform. Applications that must run on all platforms should first use comm/datamodem/dialin in calls to APIs that require a device class and only use comm/datamodem if the API returns LINEERR_INVALCALLSTATE.

The Unimodem Service Provider translates the comm/datamodem device class in calls to lineConfigDialog and lineSetDevConfig to either comm/datamodem/dialin or comm/datamodem/dialout as follows:

• Windows 2000 and later:
  • If NULL is specified in the lpszDeviceClass parameter in the call to lineConfigDialog, Unimodem assumes comm/datamodem/dialin. If comm/datamodem or tapi/line is specified in the call to lineConfigDialog, Unimodem translates this to comm/datamodem/dialout.
  • In the call to lineSetDevConfig or lineGetDevConfig, comm/datamodem is handled as comm/datamodem/dialout. NULL indicates an invalid device class.
• Before Windows 2000:
  • If either NULL or tapi/line is specified in lineConfigDialog, Unimodem assumes comm/datamodem.

The comm/datamodem/dialin class uses the structures and configurations described in the comm/datamodem device class.