How do I change the amount of rings before the voicemail comes on? I don't have a forwarding phone number and I have had this 3G iPhone for just a few months, but I was recently told it rings 8-10 times before the automatic voicemail comes on.
I don't believe that the number of rings is controllable via the iPhone. I believe you need to check and see if there is a what to do it online through your carrier, or call them and see if they can change a setting.
The only exception is the sleep/wake button. If a call comes in and you don't want to answer it, double click the sleep button to send to voicemail.
Macgirl(?) posted something a year or so ago. It was a particular alphanumeric text string that would change the number of rings. You'd change a couple of chars in that string for the various options. Sorry, that's all I remember at present.