FYI Telegram uses dubious encryption and lies about their business (for ex calling themselves a nonprofit when they aren't) and is run by a Russian oligarch who started spending on democracy-related causes after a falling out with Putin. See https://news.ycombinator.com/item?id=15281788 for example.

WhatsApp's encryption protocol (Axolotl) comes from the open source secure messaging app Signal. If you can't get people to use Signal, WhatsApp is at least much better than Telegram or Facebook messenger.