I'm using Outlook 2007 (in XP Pro).

I wanted to know if it's possible to make Outlook stop from changing
telephone numbers I input. For example, I enter something like 01 23 45 67
89, then Outlook 2007 "very cleverly" changes that to (01) 23 45 67 89.....

Come on! Not everybody needs area code. I mean, I've seen the article at
http://support.microsoft.com/?id=318575
but this so-called "canonical format" is only true for USA and Canada and a
few other countries.

Sorry to say so, not everybody on Earth follows everything Americans are
doing. Telephone numbers are one of the things that Europeans don't follow!

Moreover, it's more common for us, eg in France, to use a dot as a separator
instead of a blank-space, eg 01.23.45.67.89 for two reasons:
1. When we use the number pad, it's easier to type the dot than the blank.
Similarly, it's easier to type the dot than the dash.
2. When we copy-n-paste the number to Word doc, and when the number is at
the end of the end, dot-separated number won't get splitted off as
blank-separated number.

Sorry, Americans aren't always correct.