mr_pingu, that's what happens if you give in once. From my experience "I can't" is the best argument for an average Joe to agree on using some indie IM

Of course, when it comes to business it may be sometimes worth to bind the business number to WhatsApp. But the business number!

On my university Facebook Messenger is the most popular means of communication. The solution is... "I don't have a Messenger app, I'll read your message after a couple of days, let's better stick to something else....". But it's just thanks to the fact that my contact network is not built upon Facebook, WhatsApp...