Websites to look up phone numbers:

• spydialer.com
  • Allows you to (anonymously?) hear any phone number's recorded voicemail greeting.  I tested this and it works - but do know that Spydialer will actually place a real (automated) call to the phone number using one of Spydialer's phone numbers.
  • The name lookup feature of Spydialer is more accurate than the same feature found in numlookup.  Why do I know this?  I tested both services on a phone number I own.
  • Spydialer tells you what City and State the phone number is located in.
  • Has a "Virtual Phone" check, which shows you the probability that the phone number you're investigating is a virtual phone (aka Google Voice / burner phone).
• truthfinder.com
  • Use phone number to lookup accurate name, previous cities lived in, names of relatives, age, social media & dating profiles.
• numlookup.com
  • Numlookup does a decent job of associating a phone number with a name.  But spydialer seemed more accurate in my testing.
  • Phone numbers made using Google Voice / other burner services may or may not show the name of the phone owner using Numlookup.  For a more accurate result, I used spydialer instead.

Programs to look up phone numbers:

• phoneinfoga
  • https://github.com/sundowndev/phoneinfoga
    • git clone CloneURLGoesHere
  • Best URL:
    • https://github.com/ExpertAnonymous/PhoneInfoga
  • 2nd URL:
    • https://github.com/la-deep-web/Phoneinfoga
  • 3rd
    • https://github.com/Wes974/PhoneInfoga
  • Live demo:
    • https://demo.phoneinfoga.crvx.fr/#/
• Spiderfoot
  • Live demo:  https://spiderfoot.abdullah.cloud

• Amass?
  • https://github.com/OWASP/Amass
  • Official site:  https://owasp.org/www-project-amass/