Modem configuration functions enable you to configure a modem before making a connection. An application can set modem options and determine the features of a modem without using commands specific to any modem device. Following are the general features an application may set before making a call:
·Primary mode of operation (synchronous, asynchronous, and whether error control is enabled).
·V.42 error control (defined by CCITT recommendation V.42), including specific parameters. CCITT stands for the International Telegraph and Telephone Consultative Committee.
·V.42bis (defined by CCITT recommendation V.42bis) and MNP5 data compression.
·Time-out options, including call setup, inactivity, and buffered data delivery.
Before setting a modem's configuration, an application should determine the capabilities of the modem device by using the GetCommProperties function. This function fills in a COMMPROP structure. This structure contains both a general portion, which applies to all communications devices, and a portion that is specific to each provider subtype. For modem devices, the provider-specific portion of the COMMPROP structure is a MODEMDEVCAPS structure.
An application can get and set the current configuration of a modem by using the GetCommConfig and SetCommConfig functions, both of which use a COMMCONFIG structure. This structure contains both a general portion, which applies to all communications devices, and a portion that is specific to each provider subtype. For modem devices, the provider-specific portion of the COMMCONFIG structure is a MODEMSETTINGS structure.
After configuring a modem, an application can use the telephony application programming interface (TAPI) to actually establish a connection.
The modem configuration functions do not provide for long-term management and maintenance of a modem. Modem service providers should supply modem configuration dialog boxes for this purpose.