20 some odd Days into Samsung Galaxy S5 and I've spend way too much time on this subject. Several friends and the wife have iPhones and we're tried everything on their phones: my number has been removed from apple server, they wiped out my contact, they wiped out me as a favorite, they wiped out entire text conversation, they turned on Send As MMS, they turned the iphone off, they turned it back on, they reset network settings, they sent a text by typing in my number and not adding me as a contact first, they have updated iphone software to 7.1.1- none of this has worked - with my own two eyes and after doing what i stated above at least 4 times, I have witnessed my wifes phone send a text message to my number in Blue, indicating that somehow the phone is still getting hung up on my number being associated with imesage, which has confirmed that there is a history buried somewhere in the iphone which will not let imessage go for former iphone users. I spent 30-minutes on the phone with an "elevated" apple care person and walked through all of this. He did not waste his time and ask me do go through the motions for the 5th time - the bottom line is he stated they (apple's engineers) are working on a fix to this. DO i believe it? I'm 50/50 on actually believeing it- meanwhile I'm missing text messages from at least 20 people who rely on texting me to communicate.
At this juncture all that has worked for us is if the iPhone user turns off iMessage within settings. That's wildly inconvenient for me to ask of all iPhone users and ultimately it's their choice to do so. If other items listed about have worked for you that's awesome and you should be greatful. But then again, it could be working for some an not others and you'll never know unless you speak with the texter.
Please do not respond and state the obvious potential "fixes" which i've listed above - this is an issue for many more than 27-pages of people and it's on Apple to fix it when all items listed above have failed.