I've read through all the threads on how to deactivate iMessage, etc...so that is no longer a problem. I can now receive and send texts to iPhones. I can even have group texts with SOME of them....so this is my problem.

Most of my friends have iPhones, I have a Galaxy S4. When we group text, I can only get some messages. They have checked all their settings to where it will send an SMS message in lieu of iMessage, they've deleted and readded me as a contact, I've done the same on my phone.

I'm even able to receive texts from other iPhone users in a group setting...but only sometimes and only from certain iPhones. From what I can tell, all settings are as they should be. But nothing. We are even able to independently text each other, just not in a group. Some iPhones still think that I have an iPhone but others don't. I have literally tried everything. What could be the issue? Any solutions?