> ## Documentation Index
> Fetch the complete documentation index at: https://docs.firetone.com.au/llms.txt
> Use this file to discover all available pages before exploring further.
# The intercom
> Push-to-talk into a SIP conference room, with the microphone off until you hold the button.
The intercom turns a conference room on your PBX into a push-to-talk channel.
Everyone who dials the same channel is on the same channel, and your microphone
is shut until you hold the button down.
It is off by default, because it takes the Voicemail tab's slot. Turn it on in
**Settings › Calling › Intercom**; voicemail stays reachable from the button in
the Recents header.
## Channels and rooms
A **channel** is a conference extension your administrator has set up. The
screen lists the rooms you have used, newest first, because rejoining one is
what you will almost always be doing. **+** in the header dials a new one.
Rooms are remembered on the attempt, not on success — a channel you mistyped is
worth seeing in the list so you can tell what you actually dialled, and a room
that was busy is one you will want to try again.
## PINs
Tap a room to open it. **PIN** sets the code for that room; it is sent as tones
once the room answers, and there is a retry a few seconds later because an IVR
that is still talking drops digits sent too early.
A saved PIN is never shown back to you — the card reads `PIN saved`, and
**Change** replaces it. Leave it empty for a room that has none.
## In a channel
The channel screen is a large ring you hold. The ring tracks real audio: your
own level while you are talking, the room's while you are not. Around it:
* **Channel number** and a quality line — *Excellent*, *Good*, *Fair*, *Poor*,
*Very poor* or *Measuring…* — with the jitter and the codec in use.
* **Signal bars**, or a dash while the media stack has not rated the call. An
absent reading is shown as absent rather than as a bad one.
* **Speaker**, **Keypad** and **Leave**.
The keypad sends tones into the conference, which is how conference commands
work — `*6` to mute the room on a stock FreeSWITCH dialplan, and whatever else
yours defines.
**The microphone is open only while the button is held.** There is no
tap-to-latch, deliberately: a latch you forget is a hot microphone in a room
full of people, and the caption under the button says so on every screen.
If the channel drops, the screen stays where it is with **Rejoin** and
**Rooms**, rather than throwing you back to the list — you are still *at* the
channel, and losing your place reads like the app losing the call.
## When it refuses
A join that cannot work is refused before anything is dialled, and says which
of the three reasons applies:
* the webphone is off;
* your extension is not registered;
* no audio codec is enabled, so nothing could be offered.
The message appears on the room list under the room you tried.