Here's a roundup of articles on the Open Source Asterisk VoIP PBX.
High performance echo canceller for Asterisk VoIP systems
This article explains the general causes of echo and the methods of echo cancellation available for Asterisk. It introduces the High Performance Echo Canceller (HPEC) and compares it with the legacy Asterisk echo canceller.
Build a Linux PBX using Asterisk
- Part 1 shows how to use Open Source Asterisk PBX software and inexpensive interface hardware to build a low cost, full PBX for home or office.
- Part 2 describes support options that allow extension to enterprise phone systems.
- Part 3 introduces dial plans and how they control Asterisk operation.
Build an embedded Asterisk PBX on Blackfin
- Part 1 examines the hardware design of traditional x86 based IP-PBX systems. It then explores the design of an Embedded IP-PBX using the Blackfin, and examines its pros and cons.
- Part 2 examines the hardware design at schematic and PCB level, then take a look at the device drivers needed to connect the hardware to Asterisk running on the Analog Devices Blackfin.
- Part 3 dives deeper into the board design, and conclude with integration and testing.