The point is that you'd use this in place of your existing cell phone.
According to
the DPReview writeup, “Although we understand that the camera does not have cellular voice capabilities, it will be compatible with various VoiP apps, such as Skype, which will enable it to be used for making voice and video calls over 3G/4G or WiFi.”
I don't have any experience with using VoIP apps, but I wonder whether that would really serve as a good replacement for a phone, and whether leaving it “on” all the time would result in reasonable battery life when used as a phone.