This study is to evaluate the efficacy of a new therapy (Automatic Expiratory Positive Airway Pressure with intelligent Volume Assured Pressure Support (AutoEPAP iVAPS)) designed to treat respiratory insufficiency, respiratory failure and/or nocturnal hypoventilation with upper airway obstruction. The study will be performed in two phases: In a sleep unit and in the home environment. The new therapy will be compared against two existing ventilator therapies: "Spontaneous Timed (ST) mode" and "Intelligent Volume Assured Pressure Support (iVAPS)".