020 is the code for Greater London.
London numbers have 8 digits after the 020 area code and begin 3, 7 or 8. The next four digits after 020 may or may not identify which area of London the number belongs to. However, with number portability, you cannot reliably pinpoint the part of London that a particular number is from.
Bedford.
In the UK, area code 020 is for landlines in London. 84 would be the first two digits of an eight-digit local number.
In the UK, area code 020 is London. It is an ordinary geographic area code, not a toll-free code. '34' would be the first two digits of the 8-digit local number in London. Other countries may have domestic area codes like 02034.
01691
01931 is the telephone code for Shap, Westmorland (near Penrith in Cumbria).
UK telephone area code 0161 is Manchester, but 0161 553 is an invalid number block.
UK telephone area code 01954 (or +44 1954 in international format) is Madingley, Willingham, near Cambridge.
A UK telephone number beginning with +44 754 is a mobile.
Until the early 1990's, area code +44 21 (or 021 within the UK) was Birmingham, which is now area code +44 121 (or 0121 within the UK). There has never been an area code +44 217 (or 0217) in the UK.
01792 is the area code for Swansea
In the UK, area code 020 is London, but there are no numbers beginning with 020 2. Other countries may have similar telephone area codes.
UK telephone area codes were first assigned in 1958.
UK area code 020 is London, but there are no valid numbers beginning with 020 4, much less 020 43. Also, the area code for London is just 020, not 020x or 020xx. There are no other UK telephone area codes beginning with 020.