Mississippi prison blocked 216,320 illegal calls last month

Phone companies prefer managed-access solutions to technology that jams all cell phone reception in a certain location, which they see as too blunt an instrument.

Steve Largent, president of the wireless association CTIA, said in a blog post on Friday that managed-access technology works more like "a scalpel."

After deploying the technology, a state jail in Parchman, Miss., blocked 216,320 calls last month.

People on jail premises who try to make a call with an unregistered cell phone get a fail message: "The cellular device you are using at the Mississippi State Penitentiary has been identified as contraband and is illegal to possess under the criminal statute, 47-5-193. The device will no longer function."

The technology, approved by the Federal Communications Commission, also makes call information available for analysis so officials can do a deeper dive into who is breaking the rules.

Largent said the technology allows officials "to identify the location of a contraband phone, track its use and provide opportunities to retrieve the device and prosecute those in possession."

President Obama signed a bill into law last month, championed by Sens. Dianne FeinsteinDianne Emiel FeinsteinNearly 140 Democrats urge EPA to 'promptly' allow California to set its own vehicle pollution standards Biden signs bill to bolster crime victims fund Stripping opportunity from DC's children MORE (D-Calif.) and Chuck GrassleyChuck GrassleyBiden's bipartisan deal faces Senate gauntlet The Hill's 12:30 Report - Presented by Facebook - US gymnast wins all-around gold as Simone Biles cheers from the stands The Hill's Morning Report - Presented by Facebook - A huge win for Biden, centrist senators MORE (R-Iowa), that threatens a year of jail time to people who attempt to sneak phones to inmates.