Note: Digi Postpaid 120 & 150 subscribers who purchase the iPhone 15 series are required to add on a 90GB 5G Booster at RM10/month, applicable throughout the contract period.
Go to Settings > General > Software Update and update to the latest iOS 16.2 or newer version.
Settings > General > About and if prompted, follow the steps to update to the latest carrier settings version 53.1 or newer.