Three One Zero Zero

Finally i bought the Nokia 3100 mobile for 6100 Rs, preferring it over 3510i. It took 1 whole day and a zerox of a PAN card and Voter Identity Card to get the SIM working. Of the choice of numbers i had, i took the one which ended with 355 as it was simpler of the lot and there is a Ferrari 355.
Coming back to the title i wonder why are these mobile numbers spelled as three one zero zero instead of three thousand one hundred or something ? Is it for standardi(z/s)ation of numbers across the world ?. All our school life we learnt india's population was touching 100 crores while in the west india was touching 1 billion.
How long before a generation starts using a standard number format.

Anyways the mobile is cool and as a true geek i RTFM and it has some cool features and a bit of phosphorescence (i love to type his word, prolly coz few words this long are spelled confidently ;)). While using the various menus i realised the much hardwork and design process done behind the scenes to make it look so easy. i have been working on Swing and its quite a challenge to get user friendly graphical screens (GUI) in the first shot.