Group Messaging on iOS 9, iPhone 6

I have an iPhone 6 running iOS 9.1 and I have recently began having trouble with group messages. I can send but cannot receive responses. iMessage works but groups with non-iPhone users do not work. I have wiped/restored the phone, checked settings, reinstalled the sim, and tried everything I can think of. I have also called the provider and they reset the network settings. I am at lost, help please!