COLUMBIA, S.C. - Still unable to use jamming technology to stop smuggled cellphones, South Carolina's corrections officials are enlisting State Guardsmen to help them combat the devices they call the top security threat behind bars.

On Tuesday, Gov. Henry McMaster signed an executive order allowing South Carolina State Guardsmen to help patrol the perimeters of the state's prisons, watching for people trying to smuggle in contraband including cellphones.

The program is starting at one of the state's high-security prisons, with the goal of expanding to other facilities. Bryan Stirling, the state's Corrections director, said the program will allow him to move his officers back inside the prison, keeping institutions safer.

The partnership is the latest anti-cellphone step taken by Stirling, who has long argued that being able to jam signals from the smuggled phones — used by inmates to plan crimes and acts of violence — would be the best way to keep his employees and the public safer. Each year, Stirling's agency seizes thousands of cellphones, smuggled inside prison by visitors, errant employees, and even delivered by drone.

Wireless service providers have said that, while they support efforts to cut out inmates' illegal calls, they worry signal-blocking technologies could thwart legal calls.

The Federal Communications Commission, which regulates the nation's airwaves, has said it can't permit jamming in state prisons, citing a decades-old law that prohibits interruption of the airwaves at state-level institutions. But the agency has been softening on the issue, thanks to persistent pleas from officials including Stirling and McMaster, as well as members of Congress including Tennessee Rep. David Kustoff.

Stirling recently met in Washington with his counterparts from other states, along with wireless industry and FCC officials, to discuss ways to potentially use technology like signal jamming to fight the phones.

While continuing to push for that ability, Stirling has implemented increased searches, scanners, and even used dogs specially trained to sniff out cellphones. Last month, he announced a partnership with Richland County Sheriff Leon Lott, paying Lott's deputies to patrol woods near a maximum-security prison in Columbia, arresting people for trying to smuggle in contraband.

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