It is a device capturing and controling all the signals, which are being created by the whole system, especially the made and received phone call signals. The device is mostly used for connecting regular phone system with the Internet and backwards.
Cisco SPA112 is a dual-port voice adapter, which provides high quality VoIP services with wide set of features through a broadband Internet connection. It is easy to install and use, it works on an IP network connecting fax machines and analog phones to VoIP service providers and provides support for any additional LAN connections.