Since 2011, some Apple customers who switched from iPhone to another device have discovered that text messages sent from iPhones to their number were being intercepted by iMessage – and sent to their non-existent iPhone.
While it’s always been possible to deregister from iMessage using an iPhone – just pop your SIM in, go to settings, then Messages, and turn iMessage off – there’s been no such option for users who don’t have access to an iPhone. Thus, it seemed, were backsliders punished.
But Apple is merciful; its new Deregister iMessage website gives former iPhone users a way to delist their phone number from the iMessage service. All you need to do is head over to the website and enter your phone number; you’ll be sent a confirmation code via SMS, and tapping it into the site will switch off iMessage for that number. Simple!
Source: Apple Insider