In the US when you give out a phone number, the digits are arranged in a certain formula. One digit country code, three digit area code, three digit local code, and four digit personal number. Something like this: +1 (315) 234 – 1234.
Because this formula is universal in the US, it’s easy to see immediately if there’s a number missing. You also have a certain natural rhythm with which to say the number. Not to mention that a set of three numbers is a lot easier to look at than a list of 11.
I had an American number once that had three sets of doubles (e.g. 717 – 22 – 44- 55 – 9). I always thought it was rather clever to spout off the number like that – by highlighting the doubles. Saying it like this however created such turmoil I had to abandon practice.
“Are you sure that’s the right number of digits?!?” They’d ask, almost panicked.
It seems this pattern is absent here in China. The numbers are arranged in arbitrary sets – however the user has a whim to give them. Very often you see a phone number, and it’s just a list of 11 digits. I have to use my finger to run over the number and make sure I’ve copied each one. A long list of numbers is overwhelming when jammed together (e.g. +8613898731789). To add to this confusion cell phones have a different number of digits.
I encourage you to do some wikipedia-ing (not a good noun to verb… perhaps wiki-ing?) about the algorithm for how the numbers are determined and developed.