The entire Isle of Wight is in UK area code 01983, which is +44 1983 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 NatWest branch that has the sort code 54-41-07 is Ryde Isle of Wight. The telephone number for the branch is 0044 870 240 3399.
Newport Isle of Wight
That depends entirely on which country you're asking about. 0187 or similar is a valid domestic telephone area code in many different countries. There is no telephone area code 0187 in USA, Canada, Mexico, or Australia. UK has area codes 0187x, but they're strewn from Truro to Abergavenny and from Lochmaddy to the Isle of Benbecula; you need one more digit to narrow it down.
There is no telephone area code 185 in Russia.
The country code and area code of Isle of Arran, United Kingdom is 44, (0)1770.
The country code and area code of Isle of Benbecula, United Kingdom is 44, (0)1870.
The country code and area code of Isle of Man, United Kingdom is 44, (0)1624.
The country code and area code of Isle of Mull - Craignure, United Kingdom is 44, (0)1680.
The country code and area code of Isle of Mull - Fionnphort, United Kingdom is 44, (0)1681.
The country code and area code of Isle of Mull - Tobermory, United Kingdom is 44, (0)1688.
The country code and area code of Isle of Skye - Broadford, United Kingdom is 44, (0)1471.
The country code and area code of Isle of Skye - Edinbane, United Kingdom is 44, (0)1470.