What does default IE mean?

I’m trying to get some outbound calls out to my IAX provider and in my logs I’m seeing an error message pop up:

[Jun 9 22:13:46] ERROR[13251] app_queue.c: Received invalid event that had no device IE

Anyone know what a device IE is referring to? Nothing comes up in google other than some source code and references to internet explorer and asterisk. =/

TIA