Are there ways to "invisible" registration?

Question

User interface

Most of the portal's audience is either elderly or those for whom the words: e-mail, flogged, account, registration, etc. ... are beyond "COMPLETE"
But at the same time, many visitors are young, more or less advanced.
I would like to make simple personal accounts to receive individual information ... But if you register, then for most it is unrealistic, since they do not have mail and they will not remember passwords ...
As I understood through the phone (SMS), it is paid for me and expensive. Although it would be ideal ... Since everyone has a phone.
Are there any other options? I thought using the Fingerprint method, but I don’t know how reasonable it is. After all, if a person logs in from another device, it will not work ...
Maybe you can somehow send SMS to them through your mobile number, but I don’t know if there are such APIs for a private number ...

Answer 1

log in using your social network account and you don’t need to invent anything

Answer 2

I would not show off and did like everyone else - a standard set (phone, email, social networks).
I heard on the news that banks began to check by voice, you can still check by face.

Answer 3

basic authorization is enough - login and password
and cookies are not needed by the way

Answer 4

Maybe you can somehow send SMS to them through your mobile number, but I don’t know if there are such APIs for a private number ...

The phone is connected with a cable and you control it as a GSM modem.
Most likely at home.
Well, you implement the API to the home SMS sending server yourself.