Linux Journal: The Linux Telephony Kernel APIJan 21, 2001, 13:41 (1 Talkback[s])
(Other stories by Greg Herlein)
"A year ago, Internet Telephony was a curiosity, and many people thought it would never work for real phone calls. Now, with services like Net2Phone, Deltathree.com and DialPad providing free or extremely low-priced phone calls delivered via the Internet, Voice over IP (VoIP) has reached near-mainstream status. While Linux clients for those services are not yet available, Linux is not being left behind. With the 2.2.14 kernel, Linux has taken a bold lead in the area of computer telephony integration: we have the first modern operating system with a defined kernel-layer application programming interface (API) for telephony support. To sweeten the pot, excellent quality open-source telephony software is already using this API. You can call around the world using Linux and the Internet--and the call is free!"
"This article will explain the basics of how the telephony device drivers are integrated into the kernel in a way suitable for creating a common API across vendors. Then we'll discuss the basic ideas behind the design and function of the API, and how data and event information are dealt with separately. Finally, we'll discuss how telephony events (like ringing or picking up a handset) are handled in a process called "asynchronous event notification."