i can't say much for telegram as their encryption has been broken, and is not an openned, but whatsapp's new signal protocol designed by moxy marlinspike doesn't use sms to authenticate. It doesn't by default require authentication, but rather has it as an option and the option generates a long 80 character passcode or QR code, to be communicated in person or via some out of band communication channel, similar to threma. Maybe they are talking about old whatsapp?