>"XMPP messengers are slowly sinking"
I'm sure telegram is a good choice for your company, but "XMPP messengers are slowly sinking", I think, is a silly statement.
This is my personal opinion I've gathered from experience. I still have some friends using XMPP from Gtalk times. I have 0 new XMPP contacts for years since the fall of Gtalk. One might argue that it is still going strong, but I don't see anything proving that point. And the most authoritative indicator for ourselves is the amount of companies signed up for Jaconda. Guess having to add DNS records so XMPP is working on your domain is not helping either.