The Internet Radio Linking Project, also called IRLP, is a closed-source[1] project that links amateur radio stations around the world by using Voice over IP (VoIP). Each gateway consists of a dedicated computer running custom software that is connected to both a radio and the Internet. This arrangement forms what is known as an IRLP Node. Since all end users communicate using a radio as opposed to using a computer directly, IRLP has adopted the motto "Keeping the Radio in Amateur Radio".
Amateur radio (or ham) operators within radio range of a local node are able to use DTMF tone generators to initiate a node-to-node connection with any other available node in the world. Each node has a unique 4 digit node number in the range of 1000-8999. A real-time searchable list of all nodes worldwide (including their current status) is available anytime by viewing the IRLP Network at a Glance. As of June 2009, there are over 3,180 nodes across 7 continents.
IRLP connections are of two types: node to node, and node to reflector. Stations wishing to communicate with 3 or more nodes at the same time may accomplish this by connecting to what is called an IRLP Reflector. Reflectors are a type of conferencing system. Most reflectors on the network have 10 channels (0-9) with channel 0 being the main channel. Each reflector has a unique 4 digit node number in the range of 9000-9999. The first 3 digits consist of the reflector number, while the fourth digit represents the channel number. As of April 2007, there are 20 operational reflectors (including Echo Reflector 9990, which digitally records and plays back transmissions for testing purposes). Since most reflectors have 10 channels, there are approximately 200 unique reflector channels available for use.
IRLP Operating Instructions
Internet Radio Linking Project (IRLP) supports repeater to repeater connections. Multiple connections are available only through a reflector.
TO ORIGINATE:
1. Tune to LSR (2) – 147.315 (+) with a tone of 156.7.
2. Touch-tone in the 4 digit code for the desired node. Wait for the sign-on. Leave a 1 second pause between transmissions.
3. Key in “73” to drop the link.
4. A list of available nodes is available at http://status.irlp.net
TO RECEIVE:
1. Tune to LSR (2) – 147.315 (+) with a tone of 156.7.
2. Check the web site – you may already be connected.
3. Remote station will initiate the call.
4. You will hear “Node Connected” with the node number of the distant station.
5. Talk as you would with any QSO on VHF/UHF.
EXAMPLE – to link VE3LSR 147.315 to VE3MUS, you send the DTMF sequence 2203. If successful you will hear a beep and a connection success message. A failed attempt will result in a beep and a connection failed message. To disconnect you send the DTMF sequence 73.
Repeaters