Use *#61# SEND this will return your voice mail divert number +27... etc and the current divert delay.
Now you must note down your voice mail divert exaclty as displayed on your handset.
Your maximum divert delay on all SA networks is 30 seconds.
The code to set a 30 second delay is:
**61*your voice mail number**30# SEND
For example if your voice mail number is +278512341234123
You would use: **61*+278512341234123**30# SEND
It should be obvious that the last part of the code **30# is the delay before diverting. I'm not sure if there is a minimum but 30 seconds is the maximum.
Warning: Take care to get the divert number 100% correct or you could get someone else really miffed with your voice mail in their mailbox!!
Thank you for the very useful information! I followed your instructions and it seems to work, I have not actually phoned my number but I did check by using the *#61# before and after applying your instructions and I saw it used to be 20 seconds and now its 30 seconds, so it should work. I emailed my contact (the person who sold me my Nokia 6220 classic) and asked him how to increase from 20 seconds to 30 seconds but as usual no reply. Cell phone companies in SA are so lame!!!