how do I prolong ring time on my i phone 12

Both Voice Mail and Calls (Making and Receiving Voice Calls) are Carrier Specific features. Contact your Carrier. As far as I know, there is no such feature on an iPhone.

tiscapa wrote:

how do i prolong the # of rings on my i phone 12 before it goes to voice mail

You contact your carrier’s tech support and ask them to change it.