Welwyn Garden City is in UK area code 01707, which is +44 1707 in international format.
(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.)
The country code and area code of Welwyn Garden City, United Kingdom is 44, (0)1707.
The (01749) area code is for Wells/Shepton Mallet, in Somerset. Local numbers have six digits.
It has the area code 082.
"City code" is another term for a telephone area code, especially in the context of a telephone number in international format.
816
01792 is the area code for Swansea. The city and surrounding area are served by several different telephone exchanges for different areas and telephone companies.
Before area codes, telephone areas in North America were defined by reference to the nearest large city.
You need to ask about a specific city or town.
Bukoto is part of the city of Kampala. The telephone area code for Kampala, Uganda, is 041, or +256 41 in international format.
Telephone country code +93 is Afghanistan, and area code +93 25 (Afghan domestic telephone area code 025) is the city of Logar, south of Kabul.
They usually indicate the city (or metro area) to be called and the telephone within that city.
Most people learn their area code as children, when they're old enough to remember their home telephone number. Older telephones will have a label that shows the telephone number with the area code. Your phone bill will have your number with the area code. You can look up the area code for your city or another city on the web.
0035321 + the local number