Modem Registry Keys

The following section describes information stored in specific modem Registry keys that might help advanced users correct problems with the commands that Windows 95 uses to control a modem. To identify modem problems, you can enable Windows 95 to create a MODEMLOG.TXT file (as described in "Setting Modem Properties" earlier in this chapter), which contains responses to and from a modem when a connection was made. The MODEMLOG.TXT file might indicate when Windows 95 is sending an incorrect command string to a modem, or when a response code is not being correctly interpreted. After consulting the documentation for the modem, you might be able to adjust the modem's Registry keys to restore proper operation.

Modem Registry keys are stored under the following key:

Hkey_Local_Machine\System\CurrentControlSet\Services\Class\Modem

For each installed modem, Windows 95 creates one Registry key (starting with \0000); additional subkeys, which contain AT commands that Windows 95 uses to initialize, dial, and answer the modem; plus other entries that communications and modem drivers use.

Some of the more important entries that you can use to correct or optimize modem operation are described in the following sections. The full set of modem Registry keys and the INF file format are documented in the Windows 95 Device Development Kit.