Personally, I miss out on a lot of group chats because all of my friends have iPhones.
They’ll create a group chat, I won’t get any messages, then suddenly I’m getting a call on Saturday saying “hey are you coming to the party?” or more often than not I don’t get notified at all and end up hearing about all of the things I miss at a later time. It’s annoying, but I really hate iOS so I deal with it.
I’ve got an iMessage server running on my NAS but it’s not perfect, it requires that the iPhone user send the message to my iMessage account associated with my email, not with my phone number.
PyPush lets you link your number to your Apple Account using demo.py if you need that. It needs a cron job to sit on it for the first few weeks but after that its fine.