The latest iOS 12.1.2 released by Apple last week is reportedly not stable and is bricking out iPhones by cutting of the cellular network, so if you are planning to update your iPhone to iOS 12.1.2, you should postpone it until Apple confirms the stability of the new version of their OS.
This has not happened for the first time, as not operating systems updates are stable and needs to be fixed after launch. One such example is the recently launched Apple iOS 12.1.2 that was meant to fix and patch connectivity issues that the eSIMs of iPhone XR, XS, and the XS Max. However, on Sunday, a Mashable report reported that the updated iOS is bricking iPhones, and a number of iPhone users who updated their phones faced a bug in the new updated iOS that completely bricks out the cellular network and LTE service gets disabled altogether.
The snag has disconnected a number of users from all around the world who are unable to perform simple mobile phone activities like making calls or regular messages. A number of iPhone users from all around the world, including Europe, Asia, and South America reported about the bug through Twitter. Unlike the case of India, where Reliance Jio and Airtel both support eSIM in the latest iPhones, the iPhones recently rolled out in the US are without eSIM compatibility, which has led to network conflicts.
Apple has confirmed that the developers are working round the clock to provide a patch to the error and will soon provide a fresh update, and until then, it is suggested to avoid updating iPhones to iOS 12.1.2. Meanwhile, if you have already updated your iPhone, the Apple support team is asking users to restart and update carrier settings. Trying out a hard reset or re-inserting the SIM card might also help restoring cellular connectivity, but it is best advised to wait for a revised update from Apple.