Officials demonstrated a new system that detects and blocks calls from contraband cell phones in the Baltimore City Detention Center. (Kenneth K. Lam/Baltimore Sun video)

Drivers have reported that new cell phone blocking technology at the Baltimore City Detention Center may be extending beyond the jail's walls, despite assurances to the contrary.

Three people have told The Baltimore Sun that they were using their cell phones in the past week and a half while driving near the jail and that their calls were interrupted with a recording that said they were using an unauthorized or illegal device. State officials on Friday announced the new cell phone blocking technology, which is intended to stop inmates from directing criminal schemes while behind bars.

A representative of the company responsible for the technology said Saturday that the system was checked after the first two complaints and that no problems were found.

Tria Tucker said she was headed toward Interstate 83 after leaving her job at Johns Hopkins Hospital Friday evening, driving down East Monument Street. As she spoke on the phone with her husband, Tucker said, the call suddenly dropped, something she said was not unusual in that area in recent months. She redialed when she got to the stoplight at The Fallsway, less than a block from the jail.

"I got this recording," she said. "It was a man's voice and it said, 'You're attempting to make an unauthorized call.' It just startled me so I called back and got the same message again."

The new "managed access" system at the city jail, based on technology developed by Columbia-based Tecore Networks, is designed to capture calls before they go to the network, recognize authorized numbers, including 911, and let those calls through. Any unauthorized numbers are blocked. State officials said it went live Dec. 30 and that they held off on making a public announcement while the kinks were worked out.

Authorities have said illegal cell phones inside the detention center drive criminal activity, and said Black Guerrilla Family leader Tavon White used them to direct a contraband smuggling scheme, transfer payments and alert associates of planned searches.

Tecore officials have said their technology, which also blocks mobile data and text messages, is a legal solution to the state's long quest to eliminate illegal cell phones inside correctional facilities. The Federal Communications Commission has banned the use of cell phone jamming technology except in federal facilities, but Tecore's system lets some authorized users place calls and is not a blanket jam.

The company has said that the blocking technology would be contained to the inside of the jail and that cell phone users on the streets would not be affected. After The Sun relayed the complaints to Tecore, the company then tested cell phone calls made outside the jail walls, an official said.

"We've done a sweep of the facility and found no issues," a Tecore spokesman said.

In a test, a Baltimore Sun reporter drove around the city jail Saturday while making calls on a Verizon cell phone and an AT&T cell phone. All the calls went through normally.

Mark Vernarelli, a state corrections system spokesman, said in an email that these are the first such complaints officials they have heard about the technology.

"The system has been operating at the Metropolitan Transition Center next-door to BCDC for a year, and we have not gotten any complaints as far as I know," Vernarelli said. "Furthermore, folks have been making calls from the sidewalks outside BCDC with no such complaint."

Tucker said that while she was stopped at the red light, she also tried to access the Internet with her smartphone, and said her phone was unable to connect. She finally got back on the phone with her husband after getting on the ramp for I-83.

"I understand the need for inmates not to have cell phones, but I don't appreciate as private citizen not being able to use my phone," said Tucker, 43, of Randallstown.

She added that a citizen may need to use their cell phone in that area if their car breaks down or if they are otherwise in need.

Deborah Lancaster had a similar experience while driving down East Madison Street on Thursday evening, before the technology was announced.

Lancaster said she was headed toward the ramp for I-83 to go to a meeting in Mount Washington and got lost for a few moments by the city jail. While on the phone with her husband trying to figure out how to get to the ramp, she passed by the white walls of the jail.

"And then boom, it cut out and I got the recording that said I was using an illegal device, and I said 'Whoa, I guess they started blocking cell phones,'" said Lancaster, 58, of Parkville. "Honestly, I don't have a problem with them blocking it if that's what they need to do, but I think they should have signs" to notify those passing by that their cell phones won't work, she said.

Lancaster said she tried to redial a few times and got the same recording, which she said was a man's voice saying that use was in violation of a state statute and that the call was being monitored.

"I just think they need to know that the system isn't working the way they thought it was working and they need to fix it," Lancaster said. "It's just unfortunate. Technology's complicated."

Cockeysville resident Patricia Olmedo said Sunday that she had a similar experience Jan. 30 while driving on Madison Street. Olmedo, who was on the phone with her sister after a job interview, said that in her case, the call cut out, there was a short moment of silence and then the "violation" recording kicked in.

She was able to get through to her sister again on the ramp to I-83, and "we just laughed it off." But she doubts it was a fluke.

"It's definitely an issue," Olmedo said.

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Baltimore Sun reporter Jamie Smith Hopkins contributed to this article.