Why do my group messages keep cutting off non-Iphone users?

[iMore Question]

I have been sending a group message to three friends, two of whom have iPhones, the other doesn't. For the longest time, the messages would go through as SMS messages because I have the setting checked off to allow SMS messages when iMessage is unavailable. These group messages worked to these three recipients for over a year.

But now, whenever we send a message, it automatically cuts off the non iPhone user out of the group text when one iPhone user responds and converts the format of the text over to an iMessage. I can't figure out why this keeps happening but it keeps cutting my non iPhone friend out of the group texts.

 

[Bigeric23]

Does you friend have a birthday coming soon? An iPhone would make a great gift.

Seriously, there are some issues with group messages for non-iPhone users, and it appears it can be worse with some carriers. Has your friend switched cellular providers recently?