The Asterisk app_rpt Project
- Using open-source Asterisk PBX and Linux to build an internet linking platform to simultaneously control several repeaters at one site. Technical and contact information.
- http://zapatatelephony.org/app_rpt.html

EchoLink
- System to connect amateur radio operators to repeaters, simplex links, and other hams. Includes interface information, documentation, and node information.
- http://www.echolink.org

Internet Radio Linking Project (IRLP)
- High-end project to link repeaters worldwide via the Internet. Includes node status, hardware and linking information, and FAQ.
- http://www.irlp.net