You can also change the iPhone’s default number of rings before going to voicemail. This will result in a different number if you’re not available for an incoming call, but it could be better than waiting 20 seconds when someone leaves their name and phone number on your contact list! To change the amount of time the iPhone will ring follow these steps:
1. Open the phone app and dial *#61# on the Keypad. Press the Call button.
2. Locate this text on the screen: “Setting Interrogation Succeeded, Voice Call Forwarding, When Unanswered, Forwards to +” and record the 11-digit number after the + symbol.
3. Touch the Dismiss button. Now enter this code on the Keypad: *61*+ followed by the 11-digit Forwards to the number recorded in step 2, followed by *11 and *ringtime#. Ring time is the number of seconds you want your iPhone to ring before voicemail picks up. Your finished code should look something like this:
In the example above the ring, the time is set to 30 seconds. Press the Call button.
4. You should receive the message: Setting Activation Succeeded. Press Dismiss and next time you receive a call it will ring for a new amount of time before going to voicemail.