Offline chatting is really a thing now. However, most apps of this sort are not exactly showing the “strengths” which a technology like they were touting is supposed to show. And really, that is a shame since this is the era where “free communication” is a thing that should be fought for.
Regardless, there are a few apps which work for this exact purpose. One of those is vCinity - Chat Without Internet, a very useful app which works very beautifully for wireless chatting without any hitch at all. So yes, this one comes highly recommended. I love using this app and staying in touch with others. It's also very easy to use, as I am not internet savvy. As long as they have the app, you can chat. Simple.