Windows Embedded CE provides Unimodem as a sample TSP. Unimodem provides access to most standard modems. You can also create a customized TSP by using the TSPI.

A service provider driver is a separate dynamic-link library (DLL) and not part of TAPI. The Unimodem driver translates TAPI function calls into AT-based modem commands to configure and dial modems. TAPI manages the use of devices, ports, and call traffic by the application.

Unimodem supports Hayes-compatible AT-command-based modems. To implement other media types, such as ISDN, you must create a customized TSP.

Unimodem also provides direct cable connect (DCC) support. DCC lets you establish a direct serial or parallel cable connection between two computers to share the resources of the computer that is designated as the host. If the host is connected to a network, the guest computer also can access the network.

You set the registry keys for a specific modem and Unimodem reads the registry keys and creates a line device for that modem. For example, when a PC Card modem is plugged in, Unimodem creates a line device for that modem.

For Unimodem, the memory region that is described by the dwDevSpecificOffsetand dwDevSpecificSizemembers of the LINEGETDEVCAPSstructure is a UNIMODEM_INFOstructure, as defined in Unimodem.h. Also, the memory region that is described by the dwProviderInfoOffsetand dwProviderInfoSizemembers contains the plaintext Unicode string UNIMODEM.

Note:
The Windows Embedded CE implementation of Unimodem does not support voice modems, but you can create a customized TSP that supports them.

Note:
The Windows Embedded CE implementation of Unimodem supports hardware flow control modems only. Unimodem traces the carrier detect (CD) signal to determine if a connection exists. For software flow control modems, Unimodem is unable to detect a line drop, so the connection must be detected and dropped by an upper-layer application, such as the Point-to-Point Protocol (PPP).

See Also