Open the Settings tab and tap your name at the top ("Profile and KNOCK ID"). The "KNOCK ID" section has a "Copy ID" button. Below it, the "My link" section shows a QR code and your invite link with "Copy link" and "Share link" buttons. Your ID is also shown at the bottom of Settings in the "My UID" row.

Ask them for their KNOCK ID or invite link. Open the Contacts tab, tap the "New contact" button (person icon with a plus, top right) and paste the ID or link into the "UID" field. If you paste a link, the name is filled in automatically. Then tap "Save". If someone who isn't in your contacts messages you, they appear in Contacts under "Not in contacts": open them, enter a name and tap "Save".

Open their profile (Contacts tab → tap the person, or tap their avatar in the chat) and tap "Block" at the bottom, then confirm. You can also swipe left on them in the Contacts tab or long-press the chat in the Chats tab. Blocking works both ways: you won't be able to message or call each other. Their messages are not accepted and their calls are declined right away. To unblock, use the same place or Settings → "Blocked".

In Settings, turn off "Accept messages from non-contacts" and "Accept calls from non-contacts". Then messages from people who aren't in your Contacts tab are not shown, and their calls are declined right away.

Make sure notifications for KNOCK are allowed in iOS Settings and "Message notifications" is on in KNOCK's Settings. If notifications are blocked in iOS, the switch stays off and shows "Notifications are turned off in iOS Settings". Notifications can also be turned off for a single chat: the "Notifications" switch in the person's profile, or "Mute" in the chat list. Also check that your phone is online and, if the person isn't in your contacts, that "Accept messages/calls from non-contacts" is on. Do Not Disturb and Focus modes can also hide notifications.

Our server doesn't store messages. If the other person is offline, the message stays on your phone with a red "!" icon. While KNOCK is open and connected, the app tries to send it again every minute, and the server sends the other person a push notification to wake their app. There is no time limit: the message waits until it is delivered or you delete it. Messages are not sent to people you've blocked.

On both phones open Settings → Profile and KNOCK ID, section Profile move. On the old phone tap Move to a new phone → Show QR (Face ID, Touch ID or the device passcode is required). On the new phone tap Move from the old phone, point the camera at the QR and tap Move. When you see Move complete, close KNOCK and open it again. The QR is valid for 5 minutes: if it expires, tap Show a new QR. Moving also works between iPhone and Android.

Your KNOCK ID and name are moved. Contacts, chats, calls, files and avatars are not moved: chats are stored only on the device and are not included in iCloud backups. The profile that was on the new phone is replaced, and the old phone shows Profile disabled. Do not show this QR to anyone else: whoever scans it gets your profile.

Settings → "Profile and KNOCK ID" → "Delete Profile" at the bottom → "Delete". This erases your KNOCK ID, name and photo, all chats, messages and files, contacts, call history and settings from this phone. The server forgets this phone and stops sending notifications to it. A connection to the server is required. This can't be undone. After deleting, close KNOCK: next time you open it, a new profile with a new KNOCK ID will be created.