How to play AMR files?
First of all, get the QuickTime Player; yep nobody loves it, but we can't play the files without their wonderful codecs.
And double-click the Nullsoft DirectShow Decoder in order to pull up it's settings dialog.
Click on Configure button and add ;AMR to the extension list.
Play the files using Windows Media Player
Download and install River Past QuickTime DirectShow Filter for WMP