The new "managed access system" will allow calls from inside only to approved numbers, according to Texas Department of Criminal Justice Executive Director Brad Livingston. That complies with federal law, which prohibits electronic devices that jam all phone calls.
The Stiles Unit in Beaumont and the McConnell Unit in Beeville have seen the most contraband phones and will get the blocking system within about six months.
The new technology is similar to what's already used successfully in California prisons. It intercepts cellphone signals and has the ability to block other unauthorized communication attempts, such as emails, texts and internet log-ons, the prison agency said Wednesday. It doesn't interfere with radio communications, 911 calls or other approved electronic devices.
The system works through the vendor that handles pay phone calls made by inmates in all 111 state prisons.
The problem of smuggled phones drew attention four years ago when condemned inmate Richard Tabler, from his cell on death row, used one to threaten state Sen. John Whitmire of Houston.
"It's about time," Whitmire, chairman of the Senate Criminal Justice Committee, said at a hearing Tuesday in Austin.
Livingston said there are no plans to extend the blocking system to other prisons.
The Austin American-Statesman reported 148 smuggled cellphones were confiscated last year at Stiles and 88 at McConnell.
"These two prisons have had the most significant ongoing problems with (smuggled) cellphones, and that's why they were selected," Livingston said.
Tabler's threatening calls led to a lockdown of all Texas prisons and intense inspections to uncover contraband. In 2009, 1,110 phones were found, another 791 in 2010, 630 last year and 428 this year through July 31.
"Contraband cellphones pose a direct threat to the safety and security of correctional institutions," prison spokesman Jason Clark said. "Offenders can use cellphones to organize criminal activity, plan escapes and contact crime victims."
Besides shakedowns, the agency also uses specialized search teams, cellphone detection dogs, mobile detection technology and surveillance cameras, Clark said.
Tabler also made threats against an American-Statesman reporter, but has since written the newspaper and apologized, saying he has found God.
Tabler is awaiting execution for a double slaying in Killeen in 2004. He's also confessed to killing two others.