Instead when you end the call the persons name is still open. I almost always manually go back to my contacts list as I am done with that contact. If I need to redial they are now in my recent calls list. Very rarely will I text someone immediately after calling them which is annoying to people. This isn't a flaw by any means and I generally like the way iOS stays wherever you are so when you close something and reopen it you can pick up right where you left off, I just think it's unnecessary in this case and would be more efficient and "smart" for it to automatically close the contact once you are done.