My iphone is answered by Voicemail after 4 rings , I want to delay this to give me more time to answer calls personally
When voicemail "answers" a call is a function of the carrier, not of the phone itself. You can contact your carrier and see if they can adjust the timing. It actually doesn't have to do with the number of rings either, it is a timing issue based on how long the call is connected. Nothing you can do on the iPhone, you have to deal directly with the carrier.