John Wemlinger says he used to make cell phone calls from his driveway, where he could at least get one bar of service.

Complaints about cell phone service are hardly unique, but when Kino Springs resident Carolyn Wemlinger called her carrier, Verizon, to ask about problems she’d started having in August, she got an unusual response.

The company told her that the issue was due to cell phone towers in Mexico that are broadcasting on the same signal frequency.

“It’s like all of a sudden, we are blocked,” Wemlinger told the NI.

“Off and on, like I said, we’ve called, they’ve fixed things,” she added. Now, “they can’t fix it anymore.”

Verizon spokeswoman Jeannine Brew Braggs said the company is “aware of the issue” and that “the interference is being caused by a carrier outside the United States.”

“This is a safety issue,” Wemlinger said. “All of your first responders, how am I going to reach them? How are they going to reach me? So it goes beyond just my inconvenience. It is, I think, a real safety issue.”

A report from 10 News San Diego identified Verizon customers whose service was affected when Mexican wireless carrier Altán Redes launched its cellular service in that area in August.

And the El Paso Times reported that cell phone customers using Verizon and AT&T, as well as some local emergency responders, were affected when Altán Redes tested its network in Ciudad Juárez on Aug. 5.

In an Aug. 18 letter to the Federal Communications Commission, U.S. Sen. Ted Cruz (R-Texas) alleged that the Mexican company is interfering with signals on a 700 Mhz band, the frequency that both Altán Redes and Verizon use.

However, Altán Redes told the NI that it “is not serving commercially” in the Nogales area and said that interference in other cities was due to signals from U.S. companies that radiated across the border.

“Altán is not radiating its service signal into the U.S. territory,” a spokesperson wrote in an email.

It wasn’t clear if any other company had set up a cell phone network in the Nogales, Sonora area in recent months.

Jeff Reed, an expert in wireless communications and a professor at Virginia Polytechnic Institute and State University, commonly known as Virginia Tech, said that cell phone signals from one country could cause reception problems in another, but he said that tests would be needed to prove the existence of interfering signals.

“Essentially, that cell phone signal will end up in a handset, and (so) it’s receiving two simultaneous signals, and it just screws up the ability to extract the information out of those” signals, he said of the potential technical conflict.

Within the United States, Reed said, different wireless carriers are sometimes allocated the same frequency in adjacent states, creating the possibility for interference. In those cases, carriers cooperate to “deconflict” their signals.

Testing needed

Other residents of Kino Springs – a small community in an unincorporated area approximately eight miles east of Nogales and two miles north of the U.S.-Mexico border – said they had had ongoing problems with Verizon and other wireless carriers, but didn’t describe a major change in service quality in recent months.

Bonnie Ungerecht of Kino Springs used to be a Verizon customer, but persistent problems led her to switch to Consumer Cellular, which she said is an improvement, though she still has days without reception.

Ungerecht said her husband has a heart condition and she plans to buy a satellite-based emergency phone to be sure that she has connection if she needs to call for medical help.

Dianna Piles dropped her Verizon service earlier this year, after she kept getting charged for roaming when she hadn’t left the United States.

And Ramon Acosta, who lives next to the Wemlingers in Kino Springs but works in Mexico, has had better luck using a Mexico-based service. He said that his AT&T Mexico connection switches to roaming when he’s in the United States, but he ends up getting consistent reception.

“Honestly, even in my house I have good reception. And my house is next to John’s,” he said.

Carolyn Wemlinger said she has contacted local officials including Nogales Mayor Arturo Garino, Santa Cruz County Supervisor Bruce Bracker, and U.S. Sens. Kyrsten Sinema and Martha McSally, asking them to look into the issue.

She said that she hasn’t received any responses beyond an acknowledgement of her message.

A spokesman for U.S. Rep. Raul Grijalva, whose congressional district includes Nogales, said the representative’s office had not received any complaints related to wireless service near the border.

Reed, the Virginia Tech professor, added that the equipment needed to test for signal interference isn’t cheap, but a carrier like Verizon should be able to use instruments to prove whether or not conflicting wireless signals are really a problem in the local area.

If there is an interference issue, he said, some cooperation will be necessary.

“It’s going to take the network engineer in Mexico and the network engineer (in the United States) to meet and come to some agreement,” he said. “That’s what has to be done in the end.”

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