Stupid ring time is too short

I have a Nokia E63. My phone only rings for 5 seconds then it switches to voice mail. It is very frustrate. According to Google, the ring time varies from 5, 10, 15, 20, 25 to 30. I can change the ring duration by calling the network or sending a request via phone.

If you send a request by phone, the code is

**61*[number]**[time]#[then press the send button of your phone]

[number] is

  • optus is 321
  • vodafone is 121
  • telstra is 101
  • 3 is 333

[time] is 5, 10, 15, 20, 25 and 30