I found this really confusing when I first moved to England. I found my self writing the word 'double' until I realized they mean 5-5. I hate when I number is given as '1-double 2-double 0-treble 3-4' (or some such). It's so confusing!!!
Ha ha, I did that too at first.
I don't mind when people say "double #" but when they say "treble #", for some reason that still confuses me.
But Leeds is 0113 and I say it as "oh double one three".
I think all the confusion is because there is no standardised area code across the country. Some have three numbers, some have four, some have five. And then there are the mobile numbers!
Although, I have to admit I like that mobile numbers are different because then you
know it's a mobile number whereas in the states you can't tell from the number itself.