Open the Phone app > Keypad > Type **61*321**00# on your keypad. This code will allow you to set how long your phone rings before it goes to your voicemail > Replace 00 in the code with the number of seconds you want your phone to ring. 05, 10, 15, 20, 25, and 30 seconds.
Example- 30 seconds would be **61*321**30#
Normally this is down to provider and you normally need to contact them directly
