The iOS app doesn’t receive notifications, or notifications arrive without sound.
Go to Telegram Settings > Notifications and Sounds, make sure that notifications are ON in Telegram.
Check that global notifications are ON. Go to iOS Settings > Notifications > Telegram > Allow Notifications.
Check whether the contact or group is muted, and make sure your device's Do Not Disturb mode is OFF.
Try this trick:
First, close Telegram from the task switcher:
For devices with a home button — go to the home screen, double-tap the home button, swipe upwards on Telegram
For devices without a home button - swipe up from the bottom of the screen, then swipe upwards on Telegram
Next, go to iOS Settings > Notifications > Telegram, disable ALERTS. Re-launch Telegram, go to iOS settings, and set the alert style back to Banners. (Check out the video below the description).
If these steps don’t help you, please contact our Volunteers Support. Go to Settings > Ask a Question.