[Rosie] I forgot to add the startlingly uninteresting fact that all phone numbers must be preceeded by dialing a "1" when an area code is required in the USA. Which it always is when dialing anywhere in the five bouroughs of NYC. Even if you are in that area code when you dial. If you don't dial the "1", a recorded voice tells you to hang up and redial with the "1". This system was adopted at great expense for subscriber dialling convenience.
(Stevie) The names of London telephone exchanges used to be quite original, but have ceased to exist as such for about 40 yrs. Off the top of my head I can think of Waxlow, Pollards, Livingstone, Renown, Tudor, Museum, Bluebell, Vigilant, Speedwell. There are loads more in this vein that give you no idea of where they are. You don't need an area code to dial in London, but two four-figure numbers. There used to be a laundry near where I live whose number was Upper Warlingham 27. If it existed now it would be 01883 620027, not a London number, obviously. How boring it all is!