It is a bi-colour LED which seems to be an after thought given it sits behind the ear piece grill and on the grey phones is just a tiny point of light you can only see looking head on to the phone.
There are two types of bi-colour LED, one has 2 connections, the other has 3. A bi-colour LED with 3 pins allows both LEDs to be lit independently, giving Red, Green and Red + Green for Orange. A 2 pin LED will light Red when the current flows one way, and Green when it flows the other, meaning you can only have Green or Red and no mixture. Given there is no orange in use now I suspect the LED is a simple 2 pin affair, so there will be no way it can ever display Orange.