The telephone number +676 8500066 is being used as part of a premium-rate phone scam originating in Tonga. We know these calls come from Tonga because +676 is the telephone access code of the country.
Most people who receive a communication from this number report being given a one-ring call. This is in the hope that the person who receives the call will phone them back. Anyone who does call back will be connected to a premium-rate telephone line, for which you will be charged an extortionate rate for each minute you spend on the line.