Can the note 8 be used as a phone also?

In the US? No. However, some European versions do have the radios for voice use. If you're in Europe and have a SIM tray that's a good sign.
 
Yes, some of them. Eg my version can be (n5100, Europe)

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Can the note 8 be used as a phone also?

Check out GrooveIP in the Play Store , it works with Google Voice and you can make calls free in the US and Canada. You can buy minutes on your Google account for calls to other countries.