The phone number +676 8500175 is being used as part of a premium-rate phone scam originating from Tonga. The prefix +676 is the telephone access code for Tonga.
The number may appear on your phone as +676 8600175 and you may also be notified that the call is coming from Tonga. The scammers actually will not want you to answer. This is because they want you to phone them back so they can re-direct your call to a premium rate phone line. Therefore they will just give you a one ring call in the hope you will phone back.