SO YOU JUST GO TO ANSWER A CALL AND YOUR PHONE GOES TO ANSWER PHONE HERE IS A WAY TO EXTEND THE TIME BEFORE IT GOES TO ANSWER PHONE .

For any blackberry on o2 the the numbers to type are **61*voice mail ( normally (901) shortcut*10*30#  so enter as if dailing a call  **61*901*10*30# 

The voice mail shortcut is the three figure number you use to access your voice mail. The 30 at the end is the amount of seconds the phone will ring before diverting the call to your mail box. Also last thing 30 seconds is the maximum duration if you try to put a larger figure in then it will fail to register.

( if you have turned voicemail OFF )

To turn voicemail on 1750