Attached is the Quick Reference Guide for the standard VVX 411 handset that are on the desks of most staff.
The first thing to note, is that you DO NOT need to dial 0 to make an outside call. You simply lift the handset and dial the required number. Or dial the number and press the dial soft key if you wish to dial hands free.
Most of the other info you may need is contained in the attached QRG.