Hi !
The two first numbers of a phone number tell you where does it come from :
06 and 07 are cell phones
01 to 05 are different parts of France :
01 = Ile de France (Paris and all around it)
02 = north west
03 = north east
04 = south east
05 = south west
08 are special numbers, usually you never call because it's for TV games for example or advertising and it's expensive. They charge you more.
Hope that what you wanted to know about the 2 fist numbers...:)