20 - 40 minutes
The Earpiece Speaker would mostly not work. Had to have it on speak phone or use a earphones.
The replacement and tools I got from ifixit.com were great. It did fix my phone for about one week until I got the same issue again. It seems like there was something causing the Earpiece Speaker to stop working. I end up exchanging my phone after all.
If you still have any hardware warranty with apple I suggest do that first since the Earpiece Speaker replacement may not solve the problem long term.