The Telepresence Headset was a specially designed device built by Tony Stark to work alongside the Mark XLII Iron Man suit. Using it, Stark could relay his thoughts directly to the suit, allowing him to operate it remotely, even from a great distance.
Tony Stark first used the headset in order to have the suit interact with Pepper Potts, who had just come home, while trying to hide the fact that he was actually putting her off in order to continue working in his workshop.
Stark later used the headset to remotely control the Mark XLII to confront Eric Savin and to stop him from kidnapping President Matthew Ellis from Air Force One. Despite failing to rescue the President, Stark was able to kill Savin and save a group of passengers that had been ejected from the plane. The suit then fell apart after being hit by a semi-truck, revealing that Stark had been controlling it remotely the entire time while still on a boat with James Rhodes, heading to confront Aldrich Killian. 
The Telepresence Headset served as an interface that allowed Tony Stark to remotely pilot the Iron Man Mark XLII suit. Using the same advancements that Stark developed to allow him to summon the Mark XLII to him through mental commands and gestures, the headset can easily pick up on Stark’s thoughts and translate them more clearly to the suit, allowing him to control it from a generous distance. The headset was calibrated to Stark in a way that allows him to control the suit, as if he were still inside, with very little error or lag in its movements.
The headset appears as a narrow band that wraps around the back of Stark’s head, parallel to just above his ears, with several probes on either side that pick up on his brainwaves/mental commands. It also has a special display lens over his left eye. When activated and fully linked to the suit, the headset creates a holographic display that mimics the heads up display that Stark typically uses while inside of the suit, while also allowing him to see what the suit itself is currently seeing in real time.