Contact Phone: Track Phone Time

I want to use the Service Desk to keep track of the incoming phone calls. However in my situation I don't want to have to have the requestors prepopulated into the system. When they call in I want to fill in their name and also their phoen number. However, the phone number is a readonly field and is only populated if you select a requestor from the pupop window. Is there anyway to change this?

Also I want to keep track of key metrics like when voice mail left, when voice mail retrieved, call back and call end. Is there an easy way to do this. Some of the times can be calculated based off of ticket values liek ticket created and ticketed closed but not all. I want to be able to run reports to find the averages and for documentation.