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Maybe he is mistaking Google Talk over Google Voice?
Google Talk is an instant messaging client that you can install on your computer or smartphones and it allows you to chat with online friends and even call them via VoIP.
On the other hand, Google Voice requires an existing phone number and it adds new features: online voice-mail, text messaging, call screening, call forwarding etc. You still need a phone to use Google Voice.
And yes, sound delay may be experienced while using GT just like Skype or Viber.
Google voice does not require an existing phone number. You can port one if you want but they will let you pick a new number. Never had a delay. Don't need a phone either.