If you switched away from an iPhone, you may have issues receiving SMS sent by someone from an iOS device to your number, as those may still be sent to your iMessage account. The solution for this was to switch off the iMessage feature on your old iPhone before you switched but if you no longer have the phone with you, Apple has now released a tool that will let you deregister your number from iMessage.
Apple has quietly released a new tool to make switching between iOS and other smartphones a bit easier. The new web tool lets you instantly deregister your phone number from Apple’s iMessage system. The site, first spotted by a poster on Reddit, should solve the problem of disappearing text messages. Many former iPhone users have reported for years that they were not receiving text messages from their friends. The issue stemmed from Apple continuing to route texts through iMessage even after users had moved on to other devices. Since iMessage is proprietary to Apple’s platforms, users who switched away from iOS but didn’t disable iMessage first would no longer be able to see messages sent from friends with Apple devices. Most users who experienced the problem only had one solution: they had to entirely deregister the old device from their Apple accounts.