Google knows precisely who you are, if you have a cell phone and give them the number. Telcos boast about this, and sell that data for a price.

The only way to avoid this, is to buy a sim card anonymously, phone anonymously, and only pay cash to top up the minutes. The second you pay with a card for minutes, the telco links that and your ID is known.

And of course, if you use Google services on your phone, no way is your ID concealed for long.

This effort cancels out as soon as you give your mobile number to pretty much anyone. Most people have contacts stored at Google, so friends add your number with name, and Google again knows.

Google doesn't care about raw ID much, it cares about networks of people. Who you know, and who has who as contacts says a lot.

Anyhow. Point is, never give your phone number to anyone or you are never anonymous.