Cradle uses your operating system's notification system to tell you about new SMS and WhatsApp messages, and for the occasional system alert from the app. For that to work, your OS has to allow Cradle to show notifications, and Cradle has to be running.

Incoming calls don't use OS notifications. When a call arrives, Cradle pops its own in-call ring screen regardless of whether OS notifications are on or off. If your problem is calls not ringing, see Why am I not receiving calls? instead of this article.

Before you start

The Cradle desktop app, installed and signed in.
If you want message notifications when Cradle isn't open, make sure it's set to launch at login.

What "enabling" means

There are two layers, and both have to be on:

OS-level permission. Your operating system controls whether any app can show notifications. Cradle is one app on that list. If your OS has blocked notifications for Cradle, you won't see new-message banners or system alerts until you turn that back on.
Cradle is running. Notifications come from the app. If Cradle isn't open in your dock, system tray, or menu bar, it can't tell you a message has arrived.

Windows

Open Settings (Windows key, then type Settings).
Go to System → Notifications.
Make sure the top toggle, Notifications, is On. This is the master switch. If it's off, no app shows notifications.
Scroll down to Notifications from apps and other senders.
Find Cradle in the list and switch it On. While you're there, the Show notification banners and Play a sound when a notification arrives options control whether the notification pops up and whether it dings.
Open Cradle and ask a teammate (or a customer who's messaged before) to send you a test SMS or WhatsApp message. You should see a notification banner.

Focus assist on Windows can override this

Windows has a Do not disturb mode (older builds call it Focus assist or Focus). When it's on, notifications are silenced even for apps you've allowed.

Settings → System → Notifications → Do not disturb. Make sure it's Off.
Some setups turn Do not disturb on automatically when you're in a meeting, sharing your screen, or playing a game. Check Turn on do not disturb automatically for any rules you didn't expect.

macOS

Open System Settings.
Go to Notifications.
Scroll the Application Notifications list and click Cradle.
Switch Allow notifications On.
Pick an Alert style. Banners disappear after a few seconds, Alerts stay on screen until you dismiss them. Pick whichever you prefer for message notifications.
The first time Cradle tries to show a notification, macOS may ask you to confirm. Click Allow.

Focus modes on macOS can override this

macOS has Focus modes (Do Not Disturb is one of them). When Focus is on, only apps you've added to the Focus's allow-list get through.

System Settings → Focus. Check whether any Focus mode is currently on, especially Do Not Disturb.
If you use Focus modes deliberately, add Cradle to the Allowed Apps list for each one so new-message notifications still come through.
Focus can also be scheduled. If notifications go quiet at the same time each day, that's the likely cause.

Linux

Linux notifications vary by distro and desktop environment. Most GNOME and KDE distros have a Notifications panel in Settings, and Cradle uses the standard desktop-notification system that lives there.

Open your distro's Settings application.
Look for a Notifications section. Most distros let you turn notifications on or off per app once Cradle has shown its first notification.
If your distro has a Do Not Disturb or Quiet Mode toggle in its system tray, check it's off when you expect message notifications.

We don't have a single set of steps that covers every Linux distro. If notifications aren't appearing and your distro's Settings application doesn't have an obvious notifications panel, your distro's documentation or community forum is the best next stop.

What you should see

A small banner in the top right (Windows / macOS) or top of your screen (most Linux desktops) when a new message arrives.
A sound if you have notification sounds enabled at the OS level.
The Cradle icon in your system tray (Windows / Linux) or menu bar (macOS) shows an unread indicator.

Sending yourself a test notification

Cradle can prove whether it is allowed to reach you, without waiting for somebody to message you.

Open Settings.
Open Notifications.
Press Send a test notification.

If a notification appears, Cradle can reach you and the settings above are right. If nothing appears, Cradle is not allowed to notify you yet, and the same page has a link straight to the place on your computer where that is switched on.

This is also worth doing on a fresh install: some operating systems only list an app in their per-app notification settings once it has shown a notification at least once, so the test is what puts Cradle in the list.

The number on the app icon

The number on the Cradle icon in your dock or taskbar counts your unread messages: texts, WhatsApp messages and conversations with colleagues, added together.

That number is drawn by your computer, not by Cradle. If Cradle is not allowed to notify you, there will be no number however many messages are waiting, which is the usual reason it seems to be broken. Send yourself a test notification first, and allow notifications if nothing arrives.

On macOS there is a second switch, Badge app icon, in the same place as the notification settings for Cradle. It has to be on for the number to show. No application can read or change it, so Cradle cannot tell you whether it is on; you have to look.

If it doesn't work

Cradle isn't in the per-app notification list. Send yourself a test notification from Settings, Notifications; some operating systems only list an app in their per-app settings once it has shown a notification at least once, and the test is what puts Cradle in the list.
You're trying to get a notification for an incoming call. Calls don't use OS notifications. The in-call ring screen is the surface to watch. See Why am I not receiving calls?.
Notifications work for some messages but not others. See I'm not getting notifications for incoming messages.
Notifications were working and have stopped. A recent OS update or Focus rule is the most likely cause. Walk through the OS section above again, paying attention to the Do not disturb / Focus toggle.

Enabling Cradle notifications for messages