Living in London

I am having a heck of a time figuring out the way people write phone numbers in this country. In the US every phone number is 10 digits with a 3 digit area code, a 3 digit prefix and a four digit number. So a number in the US looks like xxx-xxx-xxxx.

Not so in the UK. First of all, the UK has the preceding 0 if you are dialling from within the UK but that is not used when dialling from outside the country. Hence our phone number in London is 0208 xxx-xxx when dialled locally but 44 209 xxx xxxx when dialled from outside the UK. This is very confusing for Americans.

However, that is not the worst of it. What I can't figure out is how many digits there should be in a standard phone number and how digits should be arranged. For example, here are some actual phone numbers taken from customer service sites around the web:

The thing to notice here is that the numbers range from 9 - 11 digits and they are arranged rather willy nilly. Sometimes the digits are grouped 4-3-4, other times it is 4-2-2-2 or 5-6, or 3-4-4. There does not seem to be any rhyme nor reason as to how the individual digits are grouped.

If anyone can shed any light on these number patterns I would be most appreciative.