Using Modem ID Strings
Your modem INF file should include every type of modem ID string that can be obtained from your modem and is supported by the applicable Windows operating systems. By doing so, you can eliminate duplicate enumerations and increase the probability of a successful installation.
For example, if your modem is a Plug and Play ISA modem, you should include the following ID strings:
ISAPNP hardware ID strings.
ISAPNP−compatible ID strings (if supported by your modem).
When specifying modem IDs in your INF file:
Use the correct format for your modem ID strings.
Include compatible IDs when appropriate. For more information about compatible IDs, see Using Compatible IDs in Modem INF Files.
Do not use legacy Unimodem IDs in Windows XP and later versions of the operating system.