Google is one of the best tool to use for hunting phone numbers, but its mostly hit or miss.
Yahoo has a feature similar to a Phone Number Guesser. Yahoo will produce a phone number when you enter a random email and it comes out to be valid. You can put a random email and click “Forgot Password” in order to recover the account. They will provide you an email address and tell you to verify it. If not then they give a phone number and tell you to verify it. You get to know the first two and last two digits of the number and also the email address. All you need is guessing and applying all possibilities of knowing the number. But actually its dangerous as when it says to verify the email or phone , it sends a verification code to the respective person and he/she will get to know that someone else is trying to use/log-in their Email ID. (Sample screenshot are attached below at the bottom of the page). So always be aware and careful regarding such codes.
LINKS for Tools
TrueCaller — https://www.truecaller.com/
CallerID Test — https://calleridtest.com/
Infobel — https://infobel.com/ (Try on INCOGNITO if you are not using a device logged in with your personal email ID) **Infobel can go International as well
Mobile Tracer — https://www.findandtrace.com/trace-mobile-number-location (CAN BE INCORRECT/MISLEADING SOMETIMES)
