When the power goes out Mulder calls Barry from his cell phone as they have lost the "captured line". Then Barry is seen talking to Mulder on a cordless phone. Cordless phones will not work without power.
Scully bases the notion of Barry's mental illness on reports of Phineas Gage, who supposedly underwent a personality change after a blasting accident drove an iron rod through his head and out the other side. However, the idea that Gage became violent, immoral, or a pathological liar, like Scully describes him, is an urban legend. Gage lived a productive life for 12 years following his accident.