What is the telephone area code for Northern Ireland?

All of Northern Ireland is UK area code 028, which becomes +44 28 from outside the UK. The remainder of the number is always 8 digits. Belfast numbers are usually either 90xx xxxx or 95xx xxxx.

As a special shortcut code, callers in the Republic of Ireland can dial Northern Ireland by substituting the code 048 for 00 44 28.

Mobiles in Northern Ireland use the same codes as mobiles in the rest of the UK. Numbers begin with +44 74 through +44 79.

(The plus sign means "insert your international access prefix here." From a GSM mobile phone, you can enter the number in full international format, starting with the plus sign. The most common prefix is 00, but North America (USA, Canada, etc.) uses 011, Japan uses 010, Australia uses 0011, and many other countries use different prefixes.)