We have quite a bit of confusion regarding the module that we are currently using for development (WP7504, with plans to migrate to the WP7603 once ready). The documentation seemed to suggest that this module had an internal codec, but I received info from Sierra Wireless support last night indicating that this module does NOT have an internal codec, but DOES have a Linux driver for an external codec (WM8944).
Our confusion centered around how to select the internal or external codec when using the mic and speaker. There was only one le_audio function for each (le_audio_OpenMic and le_audio_OpenSpeaker), so we were confused how this worked.
Now that we know our calls to OpenMic and OpenSpeaker are creating audio paths through the WM8944 external codec, I am more comfortable with this, as I now know that ALL of the code examples apply, instead of none apply as I previously thought.