If your modem and device driver support it, adaptive answering allows your modem to identify an incoming call as a fax call, or a data call, so you could use a single modem to to receive both incoming faxes and incoming Remote Access Services (RAS) calls.
Adaptive answering is disabled for the Shared Fax service in Windows Server 2003.
To enable adaptive answering in Windows Server 2003:
1. Start / All Programs / Accessories / Communications / Fax / Fax Service Manager.
2. If this is the first time you are using the fax, follow the on screen instruction if the configuration wizard starts.
3. In the Fax Service Manager snap-in, expand the + sign next to Devices and Provides.
4. Expand the + sign next to Devices.
5. Right-click the modem and press Properties.
6. Select the Microsoft Modem FSP tab.
7. Check the Enable adaptive answering if supported by the modem box.
8. Press OK.