Just method I have on my PC:
----------------
1. First, open your browser and go to the following link.
(If you want unique IP address for each account you can use them).
https://accounts.google.com/SignUpMobile
2. Choose your country phone number, enter it and then click next.
(you can reuse most SIMCARD numbers 5 times).
3. After a few seconds, you will receive a text message from Google that contains
the URL to register a new account, copy the URL address in your browser’s address bar and hit enter.
4. Fill in all the details to create your gmail account.
(just follow the steps and enter the right information in the colums)
5. Repeat the same process (probably max 5 times).
No phone number gets linked on gmail account.