In order for a computer to make a phone call to an analog phone line, a device is required to connect the computer and the phone line. In the old days, Voicent used a voice modem that was installed on a PCI slot. However, this solution no longer works for Windows Vista and later Windows OS.
Starting from release 8.4.1, Voicent supports analog phone lines by using Cisco SPA3102, which is a single line phone adapter. The device can be connected to a computer through the local network, which makes it easy to install and also ensures compatibility of various Windows operating systems.
For more info, please see Setup Cisco SPA3102 for Voicent.