There are very few USB modems that advertise support for Caller ID or that say they support Linux, OSX, or FreeBSD. A list of modems successfully used with NCID by users is in the NCID documentation.
Dualcomm Technology donated a USB modem that was tested with NCID running under Linux. The modem was plugged into a USB port, the NCID serial port was set to /dev/ttyACM0, and the NCID server started. The server was able to configure the modem and use it to get the Caller ID information.
Ethernet switch TAP
A USB Powered 5-Port 10/100 Ethernet Switch TAP was also donated by Dualcomm Technology. It was tested, using port mirroring, to obtain the Caller ID information using VoIP. NCID was able to function properly with it.
Multi-line Caller ID Ethernet Devices
NCID only supports one modem, but thanks to CallerID.com donating a developer 2-line Whozz Calling Deluxe Ethernet Link Device, a gateway was developed that supports 2-line, 4-line, and 8-line Ethernet Link Devices.
The gateway supports multiple devices. You can have any combination of 4-line and 8-line devices, with or without one 2-line device. There can only be one 2-line device connected to the gateway. A WC device provides Caller ID, start-of-call and end-of-call information. Some models even support outgoing calls.