I cannot group message using MMS, regardless of which app I use. I have tried multiple different APN settings. The group messages I try to send go out as MMS, however it never creates a conversation thread. I am using a Nexus 4 with Android Lollipop 5.0.
Group messaging, in the way you think it is, isn't actually a thing on Android. It just sends the message out to the group of people individually. When the people reply, they are replying only to you. Not to "the group". So the message only goes to you. Some specific models of phones of some manufacturers are able to rely to the entire group, but very limited. For example, on BlackBerry when I receive the message I can see who else you sent it too as well and can reply to "all" or just you.
If you want to group message properly, get an iPhone and iMessage.
The group messaging function is available on Android :-). However all members of the group must have a compatible phone, with the « Group MMS option» ON. If you send a message using group messaging and at least one contact isn't using this option, an individual message will go to each recipient (by SMS or MMS). Only the original sender will get any responses to these messages, in separate message threads.
Hope this helps :-).
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