Arizona corrections officials hope to have a dog capable of detecting cell phones in each state prison by the end of 2010, a move that would help authorities locate phones that can help further criminal activity.

The state Department of Corrections has four dogs that are either working or being trained to work in one of the state's 10 prisons to search for cell phones being hidden by inmates, officials said.

Cell phones are banned in prisons. Inmates found with phones can face disciplinary action and even criminal charges, depending on the severity of an incident in which a phone was used.

Inmates can use the phones to conduct criminal activity, including drug transactions and gang business, beyond prison walls, said Ralph Pendergast, trainer for the service-dog program and an administrator with the Corrections Department.

Cell phones also can aid inmates who try to escape or actually do escape, said Angelo Daniels, commander of the Correctional Officer Training Academy in Tucson, where the dogs are trained.

Pendergast said the department began training the dogs last May. Virginia was the first state to start using dogs to find cell phones, he said.

The dogs have helped Arizona corrections officers confiscate about 50 phones so far, Pendergast said.

The dogs are trained to identify four unique odors associated with cell phones and their components, said Kenny Vance, a service-dog trainer for the Corrections Department. The dogs also can detect batteries and phone chargers.

Vance said inmates usually get or buy the cell phones from visitors, contractors who work at the prison and staff members who sneak the phones in.

It can cost between $400 and $800 for an inmate to buy a cell phone inside a prison, Vance said.

The phones have caused more problems in prisons within the last decade as they have become smaller, Daniels said.

"When they started getting smaller and easier to conceal, that became a problem," he said. "The smaller they get, the more concerned we get."

Department of Corrections officers also use metal detectors, conduct searches and do pat-downs to look for cell phones, Pendergast said.