There's more information for users available here at QLV.it.

First a brief explanation. For the history and development of the (I)nternet (R)adio (L)inking (P)roject, please refer to the official IRLP site here, it explains far better than I ever could what it’s all about and where it came from. 

For those who want a quick explanation of it, it’s a means of linking two radios together using VOIP (Voice over Internet Protocol) with, not surprisingly, the Internet as the communication medium. If a system is set up correctly, and has sufficient bandwidth, you’ll be hard pushed to tell that the station you’re listening to is not a local one.

Unless you've used voice internet gateways before, it might all seem a little unclear, but in reality it's very simple. If you are intending to use the facilities here, all I ask is that you read these instructions first. Most of it is common sense, but it doesn't do any harm to cover some old ground.

The first and most important difference is that the nodes at G4EID are SIMPLEX voice internet gateways. That is, unlike a repeater, it can either transmit or receive at any one time, not both. If you listen to a repeater, it repeats what it hears on its input frequency onto its output frequency. In other words, listening on the repeater's output let you hear everything that's going on. On a simplex gateway, the only way you're going to hear the local station using the gateway, is if you can hear that station directly.

Imagine for example you're in Preston, with an outside aerial, and you can normally hear the gateway at S9 plus when it’s transmitting. You arrive in the shack and switch on, you hear nothing. All clear you think, and you dive in and try and connect the gateway someplace for a QSO. Think however, of the poor guy in Southport town centre, who at that very moment, is running milliwatts from his hand portable, using the gateway on a regular contact to his mate in the USA. He's getting into the gateway just fine because he's close to it, but you can't hear him. Result? You walk right over him and wreck the contact. So, golden rule number 1

RULE 1 - LISTEN, LISTEN and LISTEN again (for at least 5 minutes) on the frequency to check that the gateway really is free. If you're really wanting to find out quickly, you can key a "*3", this will then announce whether the node is free or busy. It's always better to listen first though.

Ok, so you're sure it's free and you want to use it. Now what.

For a start, don't worry about any 1750Hz toneburst, it’s not required here. The node won't "blip" up either, it's not designed that way. What is required though, is CTCSS. And the reason? Well without it, anything on the channel, for example another amateur using the frequency, (but not intending to use the IRLP node), or some local QRN will be heard by the node radio. If at that time, the node is connected to a reflector (more of which later), then that signal (whatever it is) gets re-broadcast to every other node connected to that reflector. The entire reflector channel is rendered useless to dozens of people all over the world. And the final result? Within minutes, the noise is traced to its source (G4EID) and the node is then barred from joining that reflector again. So golden rule number 2

RULE 2 - A CTCSS tone of 79.7Hz (5230 & 5240), and 123Hz (5973) is required on your transmission to access the gateway.

Ok, you've listened and established it's free, you've enabled the appropriate CTCSS tone on your transceiver, now what? Well, you need to know where you want to call! IRLP has two modes of operation. Either way, you're going to need an up to date list of nodes. The current list can be obtained by printing the one on my web site here, it's a list sorted by Country and State.

The two modes are direct, (Gateway A connects to Gateway B), or by use of a reflector. Let's take the first case because it's easier to explain.

Point to point (direct). In this mode one IRLP gateway is linked to another. It is important to remember that while a gateway at G4EID is connected to another node, no other connections (either inbound or outbound) are possible until the existing connection is closed. You establish a "link" between the gateway and another one of your choice. Whilst linked, anything that you transmit is re-broadcast on the remote end and vice versa. This enables the contact to take place. So, an example. Let’s say you've got the list and have spotted you may like to see who's around in Dallas USA. You note that the gateway's callsign is N4MSE and its associated node number is 4180. And so to the third rule.

RULE 3 - You'll need a rig capable of sending DTMF tones or a DTMF keypad.

That's because the entire system is driven by DTMF tones. Without DTMF you're lost. So, to call, you've waited and established the node is not in use, you've enabled the appropriate CTCSS on your rig, you press the PTT, announce your callsign, and "dial" 4180, then drop carrier, and listen. That's all there is to it. If you're in luck, you'll get a message back along the lines of "<callsign> <location> link on" Once you've heard this, the path is established and you're away. So, to turn a link on, simply dial the node number. If your rig doesn't have DTMF, all is not lost. Some users have been known to use their mobile phones as the DTMF source!

RULE 4 - Once a link is established, listen a while before transmitting.

Streaming audio over the Internet can introduce some delays, which can be path dependent. Always wait a little while to be absolutely sure you're not going to talk over someone at the other end.

Your contact is complete.