This is something I usually don't do. A Reblog.
I'm doing it so I have the info later on and will have to repeat it. Now you know why I have so many recipes on here - so I can bake and not have to go digging through the "Recipe Box of Doom"!
The backstory is that when Kevin went to The Isle Of Man, I borrowed a shiny old or "new to me" iPhone 4s for two weeks. The reason is that iMessage on the iPhone will do what passes for an international text for free. Google's Hangouts works that way too. But either way you have to have two people on the same hardware. Either Android or iPhone - but not mixed. Both systems are proprietary, and I believe that both will not play well with each other.
Since he had the loaner, I went off my beloved Samsung Galaxy S4 for two weeks. I came back to the S4 because I use the phone like a computer and create content on it like pictures and videos mainly for my own entertainment and use here. The camera on that iPhone has thankfully been improved in later versions, it was too saturated and too poor and grainy in low light situations. The software was rubbish since HDR didn't work well at all, but this is also iOS 6 when the current phones get iOS 8.
Got all that?
Anyway, here are the steps - and if you're coming here and want the original, here is the direct link. I have no pictures here since I followed the steps and it worked first time immediately. The steps were beyond annoying when I got to iCloud since Apple wants you to stay on their services. Removing the phone number from iCloud required hunting around in every nook and cranny of the site in order to delete the number from wherever you find it.
1) Before you leave your iPhone, turn off iMessage. This is done by going into the Settings app, selecting Message, then flicking the slider to off on iMessage.
2) Remove yourself from iCloud. On the Mac, there is (or was) an iCloud app that you could do this from. Since I am normally using Linux or Windows (in that order) I had to go to the website for iCloud. Start on the settings link (icon) and go through every single aspect, link, and sublink on there. If you see a phone number, delete it. It also argued with me to disable "Find My iPhone" in order to proceed with some of this. I did and chased my tail around until complete and I was dizzy.
I'm sorry I can't be more specific. I had to go through all of the account details manually myself.
3) Have all your iPhone friends delete and readd your contacts. Good luck. As annoying as the iCloud step was, this one may simply be impossible. Luckily for me, I had few people iMessage me during the two weeks. If your contact used iMessage to talk to you, they will not be able to recontact you until Apple's servers all realize that you have dropped off of iMessage - that could be as much as 45 days, however with me it was instant.
4) Ask your readded friends to "Send Message as Text Message" on their iPhone. Yes, seriously. They're going to wonder if they really want you as friends at this point. Hopefully you don't lose too many as a result.
5) Wait 45 days before using your new non iPhone on this number. I had to ask myself whether they were serious about this one, but apparently either I was lucky or this particular bullet is old news. It was in my case.
6) Text "STOP" to 48369 . That's the Apple support guy's hint. It worked for me immediately.
After running through all of this, my S4 is working fine. I SMS Text everywhere, I am not using iMessage anywhere.
I have read that some people on iPhones hate green text bubbles, and SMS is green while iMessage is blue. All I have to say to that is grow up since there are worse things to hate.
First world problems, really!