Here's a description from Beth Karas of how the abductor was able to keep Shawn Hornbeck -
Q: What was captivity like for Shawn Hornbeck? Is it true he tried to contact his family?
A: Shawn described his first month as particularly torturous. He was tied to a futon and had duct tape over his mouth so he couldnt yell or scream while Devlin was at work. But the abuse didnt stop there, Shawn was also sexually abused. After a month, Devlin had complete control over Shawn and slowly permitted more liberty to him. In time, Shawn had a cell phone, access to the internet, he made a friend, and even ventured out of the home. It is true that Shawn tried to contact his family via the internet. He posted a message to them asking how long they planned to search for their son. He called himself Shawn Devlin, hoping his family would take the hint. His father saw the message but didnt put it together.
http://www.hlntv.com/article/2012/1...ben-nancy-grace-mysteries-investigation-day-5