I really respect iMessage and some comments, but let's educate some followers. In Europe and Middle East, most of the people uses WhatsApp, not FB Messenger, not iMessage. Most of Apple owners even don't know iMessage and its features well. After Telegram, I honestly can't say that it is same with Whatsapp or iMessage. Telegram has so many features that should be exampled by Facebook and Apple. They had stickers when iMessage/WhatsApp has not, and now when they finally decided to put, Telegram decided to make 60 fps smooth animated stickers, which they don't have or even don't plan to do it. The only thing Telegram doesn't provide is Video Calling and I don't use it anywhere besides FaceTime, so I don't mind it.
And Telegram does this with Open Source where others may not even publish their codes. I love Telegram but most of the people uses WhatsApp in these regions.
Of course China is using WeChat, I know, I didn't see anyone here that uses WeChat, so I have no idea.
And balkans like Chechia and Serbia tend to use Viber more than WhatsApp in my travels.