MODEMDEVCAPS

The MODEMDEVCAPS structure contains information about the capabilities of a modem.

typedef struct modemdevcaps_tag {
    DWORD dwActualSize;            // size of returned data, in bytes
    DWORD dwRequiredSize;          // total size of structure
    DWORD dwDevSpecificOffset;     // offset of provider-defined data
    DWORD dwDevSpecificSize;       // size of provider-defined data
    DWORD dwModemProviderVersion;     // provider version number
    DWORD dwModemManufacturerOffset;  // offset of manufacturer name
    DWORD dwModemManufacturerSize;    // length of manufacturer name
    DWORD dwModemModelOffset;         // offset of model name
    DWORD dwModemModelSize;           // length of model name
    DWORD dwModemVersionOffset;       // offset of version name
    DWORD dwModemVersionSize;         // length of version name
    DWORD dwDialOptions;              // bitmap of supported values
    DWORD dwCallSetupFailTimer;       // maximum in seconds
    DWORD dwInactivityTimeout;        // maximum in tenths of seconds
    DWORD dwSpeakerVolume;            // bitmap of supported values
    DWORD dwSpeakerMode;              // bitmap of supported values
    DWORD dwModemOptions;             // bitmap of supported values
    DWORD dwMaxDTERate;               // maximum value in bit/s
    DWORD dwMaxDCERate;               // maximum value in bit/s
    BYTE abVariablePortion [1];       // variable-length data
} MODEMDEVCAPS, *PMODEMDEVCAPS, *LPMODEMDEVCAPS;

Members

dwActualSize
Specifies the size, in bytes, of the data actually returned to the application. This member may be less than the dwRequiredSize member, if an application did not allocate enough space for the variable-length portion of the structure.
dwRequiredSize
Specifies the number of bytes required for the entire MODEMDEVCAPS structure, including the variable-length portion.
dwDevSpecificOffset
Specifies the offset of the provider-defined portion of the structure, in bytes relative to the beginning of the structure.
dwDevSpecificSize
Specifies the size of the provider-defined portion of the structure, in bytes.
dwModemProviderVersion
Specifies the version of the service provider. The format and use of this member depends on the service provider.
dwModemManufacturerOffset
Specifies the offset of a text string that contains the name of the modem manufacturer. The offset is specified in bytes relative to the beginning of the structure.
dwModemManufacturerSize
Specifies the length of the modem manufacturer name, in bytes. The string is not null-terminated.
dwModemModelOffset
Specifies the offset of a text string that contains the model of the modem. The offset is specified in bytes relative to the beginning of the structure.
dwModemModelSize
Specifies the length of the model name, in bytes. The string is not null-terminated.
dwModemVersionOffset
Specifies the offset of a text string that gives the version and revision of the attached modem, if the provider could determine the information. The offset is specified in bytes relative to the beginning of the structure.
dwModemVersionSize
Specifies the length of the modem version string, in bytes. The string is not null-terminated.
dwDialOptions
Specifies dialing options that are supported by the modem device. This member can be zero or more of the following values:
Value Meaning
DIALOPTION_DIALBILLING Specifies that the modem supports waiting for billing tone (bong).
DIALOPTION_DIALQUIET Specifies that the modem supports waiting for quiet.
DIALOPTION_DIALDIALTONE Specifies that the modem supports waiting for a dial tone.

dwCallSetupFailTimer
Specifies the maximum call setup timeout supported by the modem, in seconds. This is the largest value that can be specified for the corresponding member of the MODEMSETTINGS structure.
dwInactivityTimeout
Specifies the maximum inactivity timeout supported by the modem, in tenths of seconds. This is the largest value that can be specified for the corresponding member of the MODEMSETTINGS structure.
dwSpeakerVolume
Specifies the speaker volume settings supported by the modem. This member can be zero or more of the following values:
Value Meaning
MDMVOLFLAG_LOW The modem supports low (MDMVOL_LOW) volume.
MDMVOLFLAG_MEDIUM The modem supports medium (MDMVOL_MEDIUM) volume.
MDMVOLFLAG_HIGH The modem supports high (MDMVOL_HIGH) volume.

dwSpeakerMode
Specifies the speaker mode settings supported by the modem. This member can be zero or more of the following values:
Value Meaning
MDMSPKRFLAG_OFF The modem supports the MDMSPKR_OFF speaker mode.
MDMSPKRFLAG_DIAL The modem supports the MDMSPKR_DIAL speaker mode.
MDMSPKRFLAG_ON The modem supports the MDMSPKR_ON speaker mode.
MDMSPKRFLAG_CALLSETUP The modem supports the MDMSPKR_CALLSETUP speaker mode.

dwModemOptions
Specifies supported modem options. This member can be zero or more of the following values:
MDM_BLIND_DIAL MDM_FLOWCONTROL_SOFT
MDM_CCITT_OVERRIDE MDM_FORCED_EC
MDM_CELLULAR MDM_SPEED_ADJUST
MDM_COMPRESSION MDM_TONE_DIAL
MDM_ERROR_CONTROL MDM_V23_OVERRIDE
MDM_FLOWCONTROL_HARD

When MODEMDEVCAPS is used to set modem options, as part of the MODEMSETTINGS structure, these values are used as follows:

Value Meaning
MDM_CCITT_OVERRIDE When set, CCITT modulations are enabled for V.21 and V.22 or V.23.

When clear, bell modulations are enabled for 103 and 212A.
MDM_V23_OVERRIDE When set, CCITT modulations are enabled for V.23.

When clear, CCITT modulations are enabled for V.21 and V.22.

For V.23 to be set, both MDM_CCITT_OVERRIDE and MDM_V23_OVERRIDE must be set.

dwMaxDTERate
Maximum DTE rate in bits per second.
dwMaxDCERate
Maximum DCE rate in bits per second.
abVariablePortion
Contains variable-length information, including strings and any provider-defined information.

QuickInfo

  Windows NT: Requires version 4.0 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Unsupported.
  Header: Declared in mcx.h.

See Also

Communications Overview, Communication Structures, MODEMSETTINGS