That's not quite how it works. You can't have a group chat that's mixed iMessage and SMS/MMS.
replyIf an iMessage user creates a group chat where not everyone is using iMessage, then it's MMS. I suppose now it could be RCS if everyone's using a device and carrier that supports RCS, but I haven't kept up with that. MMS has a bunch of limitations relative to any modern internet messaging app, so people don't want to use that.
Some people are also very reluctant to install third-party messaging apps.
Thanks. I don't actually have an iPhone, so my freshly acquired "knowledge" of this was based on reading about it on the Internet and I misunderstood what I read.
replyI don't either, but I'm familiar with the situation from talking to people who do.
replyThe obvious answer is to just use any of the many third-party messaging apps, but in the USA it seems like there's always someone who thinks a one minute setup process and tapping a different colored icon is too much effort.