This year (yet again) British Telecom and OFTEL found it necessary to change the area codes for some of the UKs biggest cities, and those of Northern Ireland.
For your easy reference, the changes are listed below
Area Old Code Old Number Changed New Code New Number
Cardiff 01222 XXXXXX 5 August 029 20XX XXXX
Coventry 01203 XXXXXX 19 August 024 76XX XXXX
Portsmouth 01705 XXXXXX 2 September 023 92XX XXXX
Southampton 01703 XXXXXX 2 September 023 80XX XXXX
London (Inner) 0171 XXX XXXX 14 October 020 7XXX XXXX
London (Outer) 0181 XXX XXXX 14 October 020 8XXX XXXX
The Northern Ireland Area Codes have changed totally.