Home Postcodes by state NSW 2308 Postcode 2308 2308 is the postcode for 2 localities in NSW: Callaghan and Newcastle University. Localities with postcode 2308CallaghanNSWNewcastle UniversityNSW Postcode 2308 State or territory New South Wales (NSW) Localities 2 Council area Newcastle Council area based on Australian Bureau of Statistics data (ASGS Edition 3), CC BY 4.0. Postcode 2307 · Postcode 2309