Recognizing the Different Types of Modem ID Strings

There are three types of modem ID strings:

• PNP HardwareID strings.
• PNP CompatibleID strings.
• UnimodemID strings.

You may choose to include only one type in your modem INF file, two of the types, or all three of the types. For more information, see General Strategies for Using Modem ID Strings.

A PNP HardwareID string uniquely identifies a particular manufacturer's modem model and is written into the registry by the Windows 95 Plug and Play system during hardware enumeration.

A PNP CompatibleID string is also written into the registry by the Windows 95 Plug and Play system during hardware enumeration if the modem is a PNP Serenum or ISA PNP type. This type of modem ID string identifies a modem model whose ID is shared by other models or OEMs.

A Unimodem ID string is obtained by interrogating a modem with AT commands and can be obtained from both Plug and Play modems and non-Plug and Play modems. This occurs during autodetection (or detection) of the modem, which happens at a different time than enumeration.