Area code 000 is not a valid North American Numbering Plan exchange or area code. It is not a valid number in any country where dialling '0' reaches an operator. It is also invalid in the European Union and many other nations where '0' is reserved as a trunk prefix and '00' as an international call prefix. In Australia, 000 is reserved as an emergency telephone number.
This code may show up as part of a number on a caller id system when receiving telemarketer outbound calls or from VoIP services, such as Skype or Vonage, because there is no requirement that caller id data represent a valid telephone number.
References
Area code 000 Wikipedia(Text) CC BY-SA