If your an aspiring PBX System Admin make sure you create two separate phones on your desktop.
One - for everyday business use.
Two - to play around on - re-configured etc.
Don't get caught screwing up transfers and stuff when you have a visitor in your office simply because you had re-programmed your own phone and had forgotten where you put the Conference Button.
It doesn't look good if it appears that you don't know how to use the phone!
Always remember that the functions on any PBX phone can be accessed via Feature Codes. Be very careful how you create, modify, open-up or restrict this functionality.