I had this argument with my then-13 year old daughter. I had forbidden her from using "the phone". She accepted the punishment.

She then proceeded on another device to show me that in no place on the official Samsung website is the device referred to as "a phone". The device is always referred to as "a smartphone" and in one place the telephone communication application is referred to as "the phone". I conceded that she made a good case and that the punishment therefore applied to the telephone communication application only.

Does the alternative password enable your phone book and phone history? If so, then yes you have unlocked the phone. If not, then you have unlocked "a phone" but not "the phone".