When the telphone code for Northern Ireland was changed to 028, the digits added were chosen to give some indication of the geographic location of the number. The areas were based on counties but with the addition of Belfast and a couple of rather odd modifications.
The whole of both shores of Belfast Lough to Whitehead on the north shore and Bangor on the south was included in the Belfast area.
Newry, in south Down, was included in Armagh.
Kilrea, in County Londonderry, was included with Antrim.
Antrim itself was included with Belfast. This last is possibly associated with maintaining the fiction that Belfast
International Airport is somewhere near Belfast.
| Area | Code | Town / City |
| Antrim (excluding Antrim!) | ||
| 028 20 | Ballycastle | |
| 028 21 | Martinstown | |
| 028 25 | Ballymena | |
| 028 27 | Ballymoney | |
| 028 28 | Larne | |
| 028 29 | Kilrea | |
| Armagh (and Newry) | ||
| 028 30 | Newry | |
| 028 37 | Armagh | |
| 028 38 | Portadown | |
| Down (excluding Newry and Bangor to Holywood areas) | ||
| 028 40 | Banbridge | |
| 028 41 | Rostrevor | |
| 028 42 | Kircubbin | |
| 028 43 | Newcastle | |
| 028 44 | Downpatrick | |
| Fermanagh | ||
| 028 66 | Enniskillen | |
| 028 67 | Lisnaskea | |
| 028 68 | Kesh | |
| Derry | ||
| 028 70 | Coleraine | |
| 028 71 | Londonderry | |
| 028 77 | Limavady | |
| 028 79 | Magherafelt | |
| Tyrone | ||
| 028 80 | Carrickmore | |
| 028 81 | Newtownstewart | |
| 028 82 | Omagh | |
| 028 85 | Ballygawley | |
| 028 86 | Cookstown | |
| 028 87 | Dungannon | |
| 028 89 | Fivemiletown | |
| Belfast | ||
| 028 10 | Belfast | |
| 028 90 | Belfast City | |
| 028 91 | Bangor | |
| 028 92 | Lisburn | |
| 028 93 | Ballyclare | |
| 028 94 | Antrim | |
| 028 95 | Belfast | |
| 028 97 | Saintfield | |