Knock
Ask to join a locked channel, and answer knocks on your own channel.
Use /knock #channel to ask the owner of a locked temporary channel to let you in. You can add an optional reason: (up to 100 characters) that is shown to the owner, for example "can I join the movie night?".
Horizon posts a message in the channel's text chat that pings the owner and shows two buttons:

@SomeUser, @Fabi is knocking on your channel: can I join the movie night?
Expires in 5 minutes
- Let in gives you access to the channel, the same way
/trustdoes. You get a DM once you are let in. - Deny declines your knock. You get a DM that your knock was denied.
If nobody answers in time, the knock expires and the buttons disappear. By default a knock expires after 5 minutes.
Once the knock is answered or expires, the message is updated and the buttons are removed:

@Fabi was let in by @SomeUser.

@SomeUser denied @Fabi's knock.

@Fabi's knock expired, no one responded.
When can I knock?
Knocking only works on channels that are locked. You cannot knock if:
- The channel is not locked (just join it directly)
- You already have access to the channel
- The channel is hidden
- You are blocked from the channel
Cooldown
You can only have one pending knock per channel. After knocking, you have to wait before you can knock on the same channel again (10 minutes by default). Server admins can change both times.
Answering knocks
As the channel owner, click Let in or Deny directly on the knock message. If you missed a message, use /knocks while you are in your channel. It shows all pending knocks with their reason and lets you answer each one from there.

Pending knocks for 🔊 SomeUser's Channel
@Fabi knocked, expires in 4 minutes: I got disconnected, can I come back?
@Alex knocked, expires in 2 minutes
Only you can see this · Dismiss message
If the server admin enabled auto-move, a member you let in is moved into your channel automatically when they are sitting in another voice channel.
Channel Moderators
Channel moderators can answer knocks too. This is enabled by default for mods that are allowed to use /trust, and server admins can change it in the dashboard.