How to get phone number to recognize you don't have an iPhone anymore?

I had the iPhone 4 but got the Samsung Galaxy s4 last week. When people that have iPhone texts me they get my texts but I can't get theirs. Their text goes to my old phone. On iPhones it is still recognizing my number is under imessages. I turned the imessages off on my old phone. I have tried doing everything I could think of. I even had people delete my contact then re-add it to their iPhone and I deleted my phone off of my apple account. Still nothing works. The only way I can text people with iPhones is if they turn their imessages off completely. This is getting really annoying but I have tried everything I could think of.

Install the imessage on galaxy s4 they have an alternative on google play for it and your problem solved. And on your old phone open imessage and deactivate your no deleting the imessage won't deactivate your no from it. You should open it and go to settings and deactivate it from there

Call apple and tell them you want to deactivate imessage.