telephone area code for eastleigh
Southampton & Portsmouth phone numbers. UK area code 023 is for Portsmouth and Southampton in Hampshire, and the surrounding areas. Locations using 023 numbers include: 1  Ashurst. 2  Bassett. 3  Bursledon.4  Cadnam. 5  Chandler's Ford. 6  Compton. 7  Cosham. 8  Eastleigh.nusually, the same 023 area code serves two separate non-adjoining areas. The Portsmouth and Southampton areas covered are some distance apart, with the 01329 and 01489 area codes used for the area in between them.