During Phone call using custom UIview

I can start a phone call using this code

var url = NSUrl.FromSt开发者_开发百科ring("tel:+xxxxx"); 
UIApplication.SharedApplication.OpenUrl(url);

it opens iphones phone call ui. can i use a custome ui during this call. for example i want to show an image.

No, you can't - this is because control is passed to the Phone.app (which is a native app written by Apple).