Just got this info from Apple Help Desk: You can reset time for incoming calls to roll over to Voice Mail. Most iPhones seem to come preset at 20 seconds, but you can change it to less than that and up to a max of 30 seconds. Here are instructions: You can choose between 5 and 30 seconds in increments of 5 (5, 10, 15, etc.). I don't think you can set it for anything longer than 30 seconds. I tried to set it for 40 seconds and got an error message. I have confirmed that this works by setting it for 30 seconds, then 10 seconds, then 30 seconds, and testing it each time by calling my iPhone and timing how long it rings before going to voicemail. First, you'll need to know your voicemail access number. The easiest way to get this is to dial *#61# and then press Call on your iPhone's keypad. The first block of text you'll see on the screen that comes up will be: Setting Interrogation Succeeded Voice Call Forwarding When Unanswered Forwards to +1XXXXXXXXXX Enabled Where +1XXXXXXXXXX is shown as an actual number - write this number down because you'll need it in the next steps. You can ignore the rest of the text that is shown for the purposes of this exercise. To change how long your iPhone rings, dial *61*+1XXXXXXXXXX*11*tt# where +1XXXXXXXXXX is the number you wrote down from the first step above and tt is the length of time in seconds for which you want your iPhone to ring. To get the + sign to show up, hold down the 0 key for a couple of seconds and release it when it turns into the + sign in the readout above. Then press Call. To give you an example, I dialed *61*+12537094017*11*30# then pressed Call to change my iPhone ring to last 30 seconds. After this, assuming you've entered everything correctly, you'll see the following message: Setting Activation Succeeded Voice Call Forwarding When Unanswered (By the way, in order to get the + character on the keypad screen is hold down the "zero" key until the + character appears) That's it! Enjoy!