Android password or phone number for logging in

Question

I created this question to collect information only.
I just read WhatsApp and Viber chat app phones and noticed it using the phone number for user login.

This is really good, because users do not need to remember passwords or usernames.

The question is a good / bad comparison with a password / username.

What good and bad to use only a phone number?
Can a user log in using anything else and then call (pc, tab) ?, restrictions?
Is this the future preferred path?
Not having a username seems like a limitation, since there is no easy way to search, for example, on facebook

Someone who has experience of both approaches will be pleased to say something.

Answer 1

I have not seen applications that use this login model. But it seems that he will alienate any Wi-Fi only tablets from the ability to use the application. The tablets with 3g / 4g on them, which I saw, can receive SMS and, thus, have a phone number, so those theoretically will still work.

As a user, I would not like this model at all. I would consider it as an attempt to get my phone number, to send me a txt that I do not want, or sell the specified number to someone else who will send me txt or cold calls that I do not want. I would prefer a username / password login. So much so that I probably just uninstall the application if it asks me to log in this way.

Edit:

"The entire application that you install on your phone has access to your phone number and all your email addresses."

- No, they do not. Both of these elements require permission to search.

AccountManger.getAccountsByType (row type)

This method requires the caller to retain GET_ACCOUNTS permission.

TelephonyManager.getLine1Number ()

Permission Required: READ_PHONE_STATE