Are there any co's that use phone verification as the sole method of logging in / authenticating on a website or checkout?

Doesn't Telegram use phone numbers for logging in? It works pretty smoothly, but I'm not crazy about sharing my phone number. I'd also see if WhatsApp does the same.

I don't think this is a good method of doing it. Personally I don't like to put my phone number anywhere - let alone sites I am not familiar with.