The most widely used 2nd factor for authentication is a phone number. When I log into my gmail account from a new PC they send me a text to confirm. Same for my

The most widely used 2nd factor for authentication is a phone number. When I log into my gmail account from a new PC they send me a text to confirm. Same for my bank account. Same for several other services. The reason they do this is because my phone is safer than a simple user / password.