Hello!
I am just looking for a way to activate group messaging in my factory unlocked iPhone 4s running 5.1 (no jailbreak). I can send group messages / group MMS to iPhones only (using iMessage). When sending to a group that includes non-iPhone, I can only send to multiple recipients, but the delivery is individual and replies are individual. Not the chat-type messaging where the whole group read all the replies.

1. I would like know how to activate or enable group messaging / group MMS so I can send to different phones (iPhones and non-iPhones) and send/receive messages in one thread (all person in the group able to read all replies)
I've been reading the web about possible solutions but cannot find a reliable non-Jailbreak one. I don't know if injecting carrier bundle into the iPhone can do this.

Please Help...

N.B. I can send/receive MMS (I edited com.apple.mms_override.plist )

By the way, I'm on T-mobile. Thanks in advance...