**UPDATE**
I came across another issue that dealt with this little white jumper. I have reached out to Mitel for clarification on this and they have confirmed that it is indeed meant to deliver power to the headset when placed in the cradle. I know that without it, it still delivers power but my guess is that it is not enough or does an extremely slow charge. (I have re-asked Mitel on this since I currently have a ticket open) I'll update as soon as they respond.
Thanks,
-Iron