Line is most well-known for their popular messaging service app on mobile devices, which is similar to the likes of WhatsApp and others, but they're newly released application called Popcorn Buzz aims to bring focus to group conversations, but through voice calls instead of messaging. It's niche is that it will let users engage in group voice calls with up to 200 participants in one call simultaneously, given you have that many people who you talk to in Line. That number isn't likely for the average users, but you may have a handful of people in your list, and it would probably be much easier to contact them all at once as it could be more efficient, assuming everyone isn't trying to talk over each other.
Calls through Popcorn Buzz are completely free which makes it all the more enticing if you're trying to limit yourself to any extra charges which could incur by using regular voice calls through your carrier service, and invites are actually pretty simple to send out with options for inviting by URL or by checking boxes next to your Line contacts for each person you want to invite to the call. At the moment Popcorn Buzz is limited to just voice calls, but group video chat is one of the features Line wants to add to the app at some point in the future. Just imagine a group video call with up to 200 of your closest friends.
Line makes it easy to identify who is talking during any call, by simply denoting the speaker with a little green dot next to their icon, similar to what you see during a Hangouts video call as the speaker in this regard also shows a little green dot. At the moment the app seems pretty bare bones, but when you think about what it's trying to accomplish, this minimalist approach to what it offers from the get go isn't all that bad, because currently there aren't really any other options for group voice calls which allow such a large quantity of people to be in a call all at once.