Missing calls on your CMF Phone 2 Pro is a real headache, especially when you're expecting something important. You check your phone and see a missed call notification, but you never heard a sound. The issue can stem from a few different places in Nothing OS, but it's usually something simple you can fix yourself.
Check the Alert Slider and Volume
The CMF Phone 2 Pro has a physical alert slider on the side. Make sure it's not set to silent. When the slider is in the top position, you should see a bell icon on your screen, indicating the ringer is on. Slide it down to mute, and you'll see a crossed-out bell. Give it a quick toggle and test with a call from another phone.
Next, check your volume levels. Even with the slider on, your ring volume might be turned all the way down. Press the volume up button on the side of the phone while it's unlocked. You should see the volume indicator on screen. Keep pressing until it reaches the maximum level.
You can also adjust this in your settings. Go to Settings > Sound & vibration and look for the "Ring volume" slider. Drag it all the way to the right. While you're there, tap on "Ringtone" and try selecting a different default tone to see if that makes a difference.
Review Do Not Disturb and Focus Modes
Nothing OS includes Focus modes, which are similar to Do Not Disturb. If one of these is active, it will silence your calls. Swipe down from the top of your screen to open the Quick Settings panel and look for the moon icon. If it's highlighted, tap it to turn it off.
For a more thorough check, go into Settings > Digital Wellbeing & parental controls > Focus modes. Here, you can see all your configured modes like Work, Sleep, or Personal. Make sure none are currently turned on. Also, look at the schedules below each mode to ensure one isn't set to activate automatically at certain times.
Disconnect Bluetooth and Check Call Settings
If your phone is connected to a Bluetooth speaker, headphones, or your car, incoming call audio might be routing there instead of your phone's speaker. The quickest fix is to turn Bluetooth off temporarily. Swipe down to open Quick Settings and tap the Bluetooth icon to disable it, then test a call.
There are also a couple of call settings that can silence rings. Go to your Phone app, tap the three-dot menu in the top right, and go to Settings. Look for "Blocked numbers" to make sure the caller isn't accidentally blocked. Also, check for a setting called "Silence unknown callers" or similar, which sends calls from numbers not in your contacts straight to voicemail.
Restart and Update Your Phone
A simple restart can clear out temporary software glitches that might be affecting your ringer. Press and hold the power button, then tap "Restart" on the screen. If your phone is completely frozen, you can force a restart by holding the power button for about 10 seconds until the screen goes black and the phone reboots.
Software bugs are often fixed in updates. Since you're running Nothing OS 3.0 on Android 15, it's a good idea to check for the latest patch. Connect to Wi-Fi, then go to Settings > System > System update. Download and install any available updates. I've seen minor audio issues get resolved with a simple OTA update.
Check App Permissions and Notifications
If you're missing calls from specific apps like WhatsApp, Telegram, or Skype, the problem might be with that app's notifications. Go to Settings > Apps > See all apps. Find the app in question and tap on it.
Select Notifications. Make sure notifications are turned on for that app. Then, tap on "Incoming calls" or the main notification category and ensure the sound is set to your desired ringtone and isn't set to "Silent." Also, check that the app has the necessary phone permissions in its settings page.
Reset App Preferences or Network Settings
If things are still not working, you can try resetting your app preferences. This won't delete any app data, but it will reset all notification settings, default apps, and background data restrictions. Go to Settings > System > Reset options. Tap "Reset app preferences" and confirm. You'll then need to re-allow notifications for your apps.
For issues that seem network-related, or if VoIP app calls aren't ringing, resetting network settings can help. In the same Reset options menu, choose "Reset Wi-Fi, mobile & Bluetooth." This will erase all saved networks and Bluetooth pairings, so you'll have to reconnect to your Wi-Fi and devices afterward.
Perform a Factory Reset
As a last resort, if you've tried everything else and the ringer is still silent, a factory reset may be necessary. This will erase all data from your phone, so it's crucial to back up everything important first. You can back up to your Google account or use a local transfer.
Once backed up, go to Settings > System > Reset options > Erase all data (factory reset). Follow the prompts to reset the phone. After it reboots, set it up as new initially to test if the ringer works before restoring your backup, as a corrupted backup file could sometimes reintroduce the problem.