Nokia Lumia 900 - My Lumia phone forwards incoming calls to voice mail too quickly.

  1. On the home screen, tap Phone > Keypad.
  2. To forward all calls to number 12345 after 30 seconds, for example, enter: **61*12345**30#.
  3. Press the Call button.

The codes mentioned are those most used by operators, but they may vary between different operators. If these codes are not supported by your network, you will receive an 'Unknown request' or 'Request denied' response from the network. Contact your operator for more details.