We have a comm channel in-game. Go to your Guild & Community window, click the drop down box in the upper left, choose Comm. At the bottom right of the Comm channel, you should see Add Channel to Window. Click the arrow button next to that and chose what window you want to see the text pop up in.
This stone is your character's "lifeline" to the Order and the IC chat channel. They cannot be destroyed or lost (yes, there are plausible reasons for this) so if you're looking for your character to fall off the grid, ask the GM for assistance.
They are about the size and shape of a hearthstone with a few differences. The stone itself is a moss-tinted grey. Rather than a swirl, the big rune in the middle is the glaive of Dor'Serrar (like the tabard). It glows dark green. The stones tap into the world's energy and send messages along the roots and natural leylines of the world. Think of them like magical telephone wires. These stones will work anywhere on Azeroth, regardless of distance. Off-world operations (such as Outland, Draenor, and Argus) do not break the stones as our magical contingent works to attune them to the different energies. This is to keep it a simple and easy IC reason for communication across distances possible.
There is a small swirly rune upon the side of the stone. Placing your thumb upon it and speaking a person's name, followed by your message, will broadcast your message specifically to that person rather than all the stones at once. This allows for IC whispers between members.
Rapidly pressing the rune on the side twice will send a distress call out from your stone. This will alert the Order that you are in trouble and will broadcast your location and vital status to the rest of the stones.