We were using LINE in the past for mobile chat. However, this has turned out to be a bad idea, TWICE. Both times, someone has joined (once while it was a public room, and another while it was invite only) and kicked everyone out of the group chat leaving it an empty room. LINE lacks any kind of Administrative abilities, and is not secure at all. Once in the group, someone can invite anyone they wish, or kick anyone they wish, even the group chat creator.
We are currently looking for another group chat type program to satisfy our mobile (mostly off-topic) chat needs. There are a few ideas that we are throwing around, and I will update this page when we have a new solution. If anyone has any good ideas, or if you would like to help us test or join, leave a comment below.
We have decided to use an app called Slack for now, it seems to be working well for what we needed, with the proper security.
If you would like join in the mostly off-topic chat, request an invite by sending me an email to firstname.lastname@example.org, just make sure to take out the 123456 part. Your email address will be shown to everyone in the group, so if you want to use a fake email to join, you may go to guerrillamail.com and get a quick one to use. The email address will be needed to accept the invite, as it is the only way to join a team on Slack.