Cell service has gotten bad in southwest Longmont and other parts of Boulder County. The reason? A 72-year-old research site needs cell carriers to back off so scientists can do their work.
The Table Mountain Field Site — those big antennas south of Nelson Road and west of Longmont — is a scientific site that does radio research under the U.S. Department of Commerce, according to its . That site, constructed in 1954, needs the airwaves to be quiet when it comes to radio and cell service so it can do its research, like when it looked into the potential for 5G waves to interfere with airplanes in 2023, the website says.
Residents started complaining of bad service since at least the beginning of September, according to multiple social media posts over the past month. One of them, Logan Porvaznik, lives in west Longmont near Vance Brand Airport. A DoorDash and Uber Eats delivery driver, Porvaznik said the dead zone seemed to show up out of nowhere, and now it affects his bottom line.
“There are some times when I have to make a delivery, and I can’t actually mark it as delivered,” Porvaznik said of residences in southwest Longmont. “I’ve not been able to work in that part of town. It’s a big hit.”
Porvaznik also said the cell coverage problems mean he can’t talk to his girlfriend while she drives home from work in Boulder, and that it feels like the problem keeps getting “worse and worse.” Before hearing that the problem was affecting many people in the county, Porvaznik was considering switching carriers, or even getting a new phone to try to go back to normal, he said.
Federal Communications Commission regulations protecting the Table Mountain Site from burdensome cell and radio signals in the area have been on the books since as far back as 1978, according to the regulation’s publication date in the . But, the Institute for Telecommunication Sciences, the group that operates the antennas, only found in 2024 that mobile carriers were exceeding federal signal limits for the area, according to spokesperson Stephen Yusko.
That interference could disrupt the Institute’s research on millimeter-wave signals, which are used in some of the strongest 5G antennas that people’s mobile phones can connect with, according to the Institute’s site. It could also pose problems for research conducted at the site by the U.S. Geological Survey and the National Oceanic and Atmospheric Administration.
Since January 2025, the Institute has worked with mobile carriers — such as T-Mobile, Verizon and AT&T — to bring their signals back into federal compliance with the region the FCC designated as a Radio Quiet Zone, Yusko wrote in an email statement.
The result, though, is poorer cell coverage for Boulder County residents who were used to getting good service throughout the county’s eastern plains. According to Yusko, any fixes will be up to the carriers themselves.
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It’s not clear, though, what the carriers can do to bring back the coverage Longmont and other Boulder County residents had come to expect.
“We know how frustrating it is when connectivity doesn’t work the way you expect, and we understand the concerns we’re hearing from customers and communities in the area,” T-Mobile wrote in a statement to the Daily Camera. “We have now achieved the required federal thresholds, and our engineering teams are working on longer-term network solutions designed to improve coverage and capacity while maintaining compliance …. That work is underway…”
Local officials, like Longmont councilmember Jake Marsing, are trying to get better answers, and he said he is willing to help carriers get the permitting or infrastructure coordination they need to get residents the coverage they expect.
“People should be able to call their kids, their doctor and call 911 anywhere in this city,” Marsing wrote in a statement. “That’s a pretty basic expectation in 2026.”
Longmont Mayor Susie Hidalgo-Fahring is expected to address the cell service issue at Longmont City Council on Tuesday, according to Marsing.
