I've been living with a pet-peeve for ages & finally had enough & adressed it.

The ring time on my mobile was *extremely* short - so short that I'd often miss calls, as they would go to voicemail before I had time to (find &) pick up my mobile within 30 seconds (or so).

To set the ring time on your mobile, use the following MMI code:
**61*+64222022000**XX#

(where XX is the ring time)

Hope this helps someone else too.

Please feel free to add your own discovered MMI codes 
- J