The easiest way to avoid this problem is to make sure you turn off iMessage on your iPhone before you switch devices then you don't have this problem in the first place.
As someone who regularly switches between Android and iPhone, this is the answer everyone is looking for. It's as simple as turning it off before you switch to a device which is SMS-only.
Moreover, before you sell your device or give it away, make sure you turn iMessage off.
When I switched from an iPhone to an Android handset, I found that I not only had to switch off iMessage, I had to switch it off while my SIM card was still in the iPhone. Switching iMessage off after the fact didn't seem to work.
https://discussions.apple.com/thread/3392014?start=15&tstart...