Liverpool is in UK area code 0151, which is +44 151 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.)
UK area code 01204 is Bolton, Lancashire. A number beginning with 01204 532 is most likely a BT line in Bolton, but with number portability any specific number could be served by any local operator, at any address in the Bolton 01204 area.
01931 is the telephone code for Shap, Westmorland (near Penrith in Cumbria).
01691
017724 is too long for telephone code in the UK, 01772 is the code for Preston, Lancashire.
UK telephone area code 0161 is Manchester, but 0161 553 is an invalid number block.
First dial the International Access Code. This is 011 from Canada. Next dial the UK Country Code: 44. Next dial the area code and local number, OMIT the initial zero from the area code. Lanchashire has several area codes. You'll need to specify which town or city if you want further information.
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.
01792 is the area code for Swansea
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.
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.