This story was co-published with PBS Frontline, which will air a film version today. Check local listings.

In the spring of 2008, AT&T was racing to roll out a new cell phone network to deliver music, video and online games at faster speeds.

The network, known as 3G, was crucial to the company’s fortunes. AT&T’s cell service had been criticized by customers for its propensity to drop calls, a problem compounded when the company became the sole carrier for the iPhone.

Jay Guilford was a tiny but vital cog in the carrier’s plans.

On a clear evening in May, Guilford was dangling, 150 feet in the air, from a cell tower in southwest Indiana. He had been sent aloft to take pictures of AT&T antennas soon to be replaced by 3G equipment.

Work complete, Guilford sped his descent by rappelling on a rope. Safety standards required him to step down the metal pole, peg by peg, using a special line that would catch automatically if he fell. But tower climbing is a field in which such rules are routinely ignored.

“Bouncy, bouncy,” Guilford, 25, called jovially to men on the ground.

Then, in an instant, the hook attaching the rope to the tower – broken and missing its safety latch – came loose. Guilford plummeted to the gravel below, landing feet first. The impact shattered his legs and burst his aorta. He bled to death in minutes.

Cell phones are our era’s ubiquitous technology device. There are more active cell phones in the U.S. than people.

An investigation by ProPublica and PBS “Frontline” shows that the convenience of mobile phones has come at a hefty price: Between 2003 and 2011, 50 climbers died working on cell sites, more than half of the nearly 100 who were killed on communications towers.

Yet cell phone carriers’ connection to tower climbing deaths has remained invisible. They outsource this dangerous work to subcontractors, a practice increasingly common in risky businesses from coal mining to trucking to nuclear waste removal. If you look up the major cell carriers in the Occupational Safety and Health Administration’s database of workplace accident investigations, you will not find a single tower climber fatality listed.

Guilford didn’t work for AT&T – he worked for a subcontracting outfit affiliated with a bigger subcontractor hired by a construction management firm working for AT&T.

For each tower-related fatality since 2003, ProPublica and PBS “Frontline” traced the contracting chain from bottom to top, reviewing thousands of pages of government records and interviewing climbers, industry executives and labor experts.

We found that in accident after accident, deadly missteps often resulted because climbers were shoddily equipped or received little training before being sent up hundreds of feet. To satisfy demands from carriers or large contractors, tower hands sometimes worked overnight or in dangerous conditions.

One carrier, AT&T, had more fatalities on its jobs than its three closest competitors combined, our reporting revealed. Fifteen climbers died on jobs for AT&T since 2003. Over the same period, five climbers died on T-Mobile jobs, two died on Verizon jobs and one died on a job for Sprint.

The death toll peaked between 2006 and 2008, as AT&T merged its network with Cingular’s and scrambled to handle traffic generated by the iPhone. Eleven climbers died on AT&T jobs in those three years, including Guilford.

“I don’t think there’s any question that the pressure to build out the network has been a contributing factor to fatalities,” said Steve Watts, who worked as a risk manager at AT&T until 2007.

Current AT&T officials would not comment on the Guilford case and declined requests to be interviewed for this story, as did officials at the other major cell carriers.

In a written statement, AT&T said it required its contractors to follow safety regulations and that cell tower fatalities had decreased in recent years even as carriers have continued to make expensive improvements to their wireless networks. There were no fatalities on AT&T jobs last year, the statement noted.

“Worker safety has always been a hallmark of AT&T,” the statement said.

The carrier and its construction management firm, General Dynamics, had no employees on site when Guilford died – only subcontractors. Neither was sanctioned in OSHA’s investigation after the accident.

OSHA cited just one company for safety violations in the case: Nashville-based Phoenix of Tennessee, the parent company of All Around Towers, the subcontractor that had managed the climbing crew. Inspectors concluded that Phoenix of Tennessee had not removed broken equipment from the site or addressed unsafe work conditions in plain view. The company paid a fine of $2,500.

All Around Towers went out of business soon after the accident. Two of its owners, who started a new tower company called ETA Systems, declined to answer questions from ProPublica and PBS “Frontline.”

Kyle Waites, the owner of Phoenix of Tennessee and part-owner of All Around Towers, said he sent climbers for retraining and purchased new safety equipment after Guilford’s fall.

“Do I feel responsible to a degree? I think everybody does that was involved with it,” Waites said. “What caused Jay’s death was a chain of events that all could have, and should have, been prevented.”

But Waites said that those off site, like himself, could only do so much to ensure climbers’ safety – it had been up to All Around Towers, and Guilford himself, to follow the rules.

“Once you leave men alone, the men have to police themselves,” he said.

Guilford left behind a fiancée, Bridget Pierce, and two young children, Emily, now 7, and Aidan, now 5.

Under policies provided by Phoenix of Tennessee, Pierce received $200,000 in life insurance, but was denied worker’s compensation because an autopsy showed Guilford had recently smoked marijuana. Lawyers advised Pierce not to sue because of the drugs.

In her house on the outskirts of Murfreesboro, Tenn., Pierce keeps a framed picture of Guilford posing atop a cell tower. He’s smiling, his fists pumping in the air. After years of moving furniture and delivering pizza, he had loved his $10-an-hour climbing job, she said.

Still, Pierce cannot escape the sense that Guilford had been a disposable part to the companies that rely on men like him to go up cell towers.

“It’s like he didn’t exist,” she said. “They just pass the ball off to the next person. Everybody in this process should be held accountable.”

* * *

Until the 1990s, most tower work involved radio and television towers, which can be more than 1,000 feet high. Some phone companies employed staff climbers to work on microwave towers used for long-distance calling.

With the proliferation of cell phones, the pace and volume of tower work spiked.

Carriers blanketed the country with cell sites to extend service to the most remote areas. There are now more than 280,000 sites nationwide, up from 5,000 in 1990. Many advances in service require switching out antennas and doing other upgrades.

The surge of cell work forever altered tower climbing, an obscure field of no more than 10,000 workers. It attracted newcomers, including outfits known within the business as “two guys and a rope.” It also exacerbated the industry’s transient, high-flying culture.

Climbers live out of motel rooms, installing antennas in Oklahoma one day, building a tower in Tennessee the next. The work attracts risk-takers and rebels. Of the 33 tower fatalities for which autopsy records were available, 10 showed climbers had drugs or alcohol in their systems.

“It’s the wild, wild west of the technology industry,” said Victor Guerrero, a construction project manager and former climber. “You’ve got to have a problem to hang 150 feet in the air on an 8-inch strap. You’ve got to be insane.”

Since 2003, an analysis of OSHA records show, tower climbing has had a death rate roughly 10 times that of construction. In 2008, the agency’s top administrator, Edwin Foulke, called tower climbing “the most dangerous job in America” at an industry conference.

“That’s an alarming incidence of fatalities,” said John Henshaw, who preceded Foulke as OSHA’s administrator from 2001 to 2004. “It shouldn’t be tolerated.”

The same handful of factors crop up again and again in agency investigations of worker deaths, our reporting found. In two dozen cases, for example, inspectors found that workers on sites where fatalities occurred had received inadequate training, records show.

Climbers typically earn $10 or $11 an hour, yet some subcontracting companies demand they pay for their own safety gear, deducting money from their paychecks.

Faulty or misused equipment was identified in almost one-third of the tower-related deaths since 2003, OSHA records show. In April 2008, after 46-year-old William Bernard died in a 75-foot fall, an inspector found that his safety harness, rusty with wear, had a defective hook.

Carriers sometimes power down cell sites when climbers are on them, so subcontractors often work overnight, when fewer customers will notice disruptions. Jeremy Combs, 33, fell to his death just before midnight in September 2008, on a job where the crew wore headlamps and raced to meet an accelerated timetable, OSHA inspectors found.

Time pressure often leads tower hands to use a technique called free-climbing, in which workers don’t connect their safety harnesses to the tower. This allows them to move up, down and around more quickly, but leaves them without fall protection. In more than half of the tower fatalities we examined, workers were free-climbing, even though government safety regulations strictly prohibit it.

Wally Reardon, a veteran climber who quit in 2002, takes photos and video whenever he spots workers free-climbing to raise awareness about the practice. It often occurs within clear view of on-site supervisors and has their tacit approval, he said.

“Even the safest people I’ve worked with in the industry eventually will cave to it,” he said of the pressure to use such shortcuts.

After 32-year-old William Knorr died in a 2004 fall, OSHA found that his supervisors had “completely disregarded” safety regulations to save “Time, Work, Money,” an investigation report said. “Was there a motive? Faster and Easier.”

No one knows better than Ray Hull how time pressure can lead to injuries.

In November 2003, Hull, then 35, was hired by a subcontractor to help build a 350-foot cell tower for Nextel in a cornfield near Fremont, Neb. The job needed to be done by midnight on Thanksgiving, just seven days away.

The project ran into a series of problems. The crane operator, deciding it was too windy to work, took his crane and left. Hull found replacement equipment, but it was in Texas, more than 15 hours away. Setting out to retrieve it, Hull and another tower hand, Frankie Ketchens, drove nonstop, taking turns behind the wheel.

When they arrived back at the site two days later, there was a Nextel truck near the tower’s base. Hull assumed the carrier wanted to make sure the job was on time. He was mistaken – the driver was just a technician – but instead of returning to their motel to sleep, Hull and Ketchens immediately went to work.

When Hull had climbed 240 feet to add a section to the tower, Ketchens pulled the wrong lever on equipment hoisting a huge piece of steel. The equipment broke away from the tower and fell to the ground – with Hull attached. His safety harness broke his fall momentarily, then snapped.

Hull has no memory of falling or hitting the ground. When he came to, he saw Ketchens above him. “I said, ‘Frankie, I can’t live through this … You need to tell my family I love them,” Hull recalled.

According to court records, Hull suffered massive internal injuries. He sued three companies involved with the project, and received a settlement from the subcontractor that hired his firm.

His case against Nextel was dismissed, however. In court documents, the carrier argued that its final project deadline was actually a month later and hadn’t compelled the climbers to take undue risks.

The carrier also said it wasn’t responsible for Hull, who, as a subcontractor, was “three entities removed from any relationship with a NEXTEL entity.” (Nextel merged with Sprint in 2005. Sprint declined to comment on the case.)

Hull’s injuries left him unable to climb towers. He started climbing at 14, following his father and grandfather into the business. Nearly nine years after the accident, he still misses it horribly. “There’s probably not a human being alive that loved their job as much as I did,” he said. “Everything that I could do was taken from me.”

Watching an OSHA video of the accident scene for the first time late last year, his eyes welled with tears.

“It was a bad day. Or a good day depending on which way you look at it,’ he said. “I walked away from it.”

* * *

Cell carriers give several reasons for why they outsource tower work: Building and maintaining towers, though crucial to cell service, isn’t part of their core business. Contractors have greater expertise with construction. It’s more economical to hire workers where and when needed, given the up-and-down volume of work.

“It makes good business sense for them to contract it out,” Watts said.

But handling tower work this way also insulates companies atop the contracting chain from legal and regulatory consequences when there are accidents, industry insiders say.

OSHA has the authority to cite carriers if it can prove they had direct control over work or knew of safety violations. Yet, even though some carriers set prices and timetables for tower jobs – and many of their technical specifications, down to how to color code coaxial cables – their supervisors typically stay off-site and do not manage jobs directly.

The oversight system provides an incentive for them not to know too much about what’s happening on work sites, labor experts say.

“Information that there are unsafe practices makes you responsible for fixing those practices,” said Thomas Kochan, a professor of management at MIT.

AT&T contracts spell out precisely what level of responsibility it wishes to have over each aspect of tower projects. In a table called the Division of Responsibilities Matrix, the carrier lists more than 100 tasks and, for each one, indicates if AT&T wants responsibility for it, to be consulted on it, or to be informed about it.

In three-year contracts issued in 2008 that were examined by ProPublica and PBS “Frontline,” the matrices were blank for safety-related items, such as ensuring that OSHA standards were met. Contractors told us they understood this to mean the carrier wanted no involvement with them at all. AT&T declined to answer questions about the matrix.

In addition to outsourcing tower work, some cell phone companies funnel jobs through middlemen known as turf vendors. AT&T does this on almost all tower jobs; in 2010, Sprint moved toward a similar system.

Turf vendors – typically large construction management firms such as General Dynamics, Bechtel and Nsoro – oversee batches of tower projects, subcontracting out the climbing work to smaller companies.

Ed Reynolds, AT&T’s president of network services until 2007, said middlemen lessened the administrative burden on carriers, giving them one big contractor to deal with instead of dozens of little ones.

“You got one throat to choke,” he said.

But subcontractors often contract out jobs to other subcontractors. As jobs are passed down from one company to the next, there’s less ability to control who’s actually doing the work, said Mark Hein, who has worked for several turf vendors as a construction manager.

When he was sent to check on cell sites last year, Hein discovered many subcontractors that hadn’t been approved by the turf vendor.

“I’d show up on site and expect to find Company A and instead find Company Z,” he said.

Many of the crews he came across weren’t taking the most rudimentary safety precautions.

“They didn’t have their hardhats, they didn’t have safety glasses, they didn’t have safety gear,” he said. Many of the climbers lacked training certificates.

Hein did not have time to visit every site he was assigned to supervise – there were just too many, he said, a common lament among other construction managers for turf vendors.

Turf vendors also take a cut of what carriers pay for tower work – sometimes 40 percent or more – so subcontractors say they make less on these jobs.

In AT&T contracts examined by ProPublica and PBS “Frontline,” the carrier requires turf vendors to reduce their prices 5 percent each year over the three-year term of the contract. These reductions are typically passed through to subcontractors, industry insiders said.

“Guess who takes the hit? The next level [down],” said a construction manager for a turf vendor. “I’m not going to reduce the amount of money I take.”

Chris Deckrow, who owns a small climbing company in Michigan, showed ProPublica and PBS “Frontline” the price sheet for AT&T jobs. For the task of installing a remote radio head, the price sheet said, the carrier would pay the turf vendor $187 and the turf vendor would pay the subcontractor $93.

Deckrow said his company – which often works as a subcontractor of a subcontractor – has been paid as little as $40 for installing remote radio heads. Overall, he said, he makes less than half the money working for a turf vendor that he would make working directly for a carrier.

Hein said the difference in pay dictates which companies take jobs involving turf vendors.

“Rather than paying this amount to this guy, who’s really qualified and … has a great reputation, they hire this person over here because he’s available right now and he’ll do it for what we want him to do it for,” he said.

Verizon, which hires subcontractors directly, tends to work with the same select group of climbing companies over and over, paying them more, subcontractors say. David Coleman, an industry analyst at RBC Capital Markets, described becoming a Verizon subcontractor as the “golden ticket.”

Several subcontractors complained that they had to cut corners to turn a profit on turfing jobs, using three-man crews instead of four, putting in 18-hour days, hiring less experienced men and working through inclement weather.

Reynolds, who now works as an industry consultant,dismissed such gripes. “There’s enough subcontractors out there willing to work,” he said. Those that don’t like the prices, he said, will “do something else.”

Buckling on a harness before mounting a 300-foot tower last March to check out a broken light, Deckrow described how tight margins erode safety.

He said he’s struggled to pay insurance premiums, cut back on training programs and delayed buying new safety gear for his men.

“This is stuff they have to wear every day in order to live through the day,” he said. “We would love to replace it every year, every two years … It’s not in the budget.”

Deckrow said earlier this month that he had decided to close his company rather than making further cuts.

“I want to be able to not worry about my guys not coming home,” he said. Throughout the industry, companies are choosing between safety and staying in business, he added. “If we’re not properly maintained or trained, then people will die. It’s only a matter of time.”

* * *

The worst years for cell site fatalities in the last decade were 2006 and 2008.

There is no way to correlate these figures with workloads or to compare one carrier’s tower work to another’s because such information is proprietary. As of mid-2011, the four major carriers had varying numbers of cell sites: Verizon had 44,250, T-Mobile had 50,143, AT&T had 56,070 and Sprint had 67,500, according to data from US Wireless 411, a report by UBS.

Most inside the industry agree, however, that AT&T faced unique challenges and pressure to build out its network.

After Cingular merged with AT&T in 2004, the combined company (which later took the AT&T name) had to join its network systems, adjusting virtually every single cell site. Reynolds compared it to replacing the engines of a 747 in mid-flight.

In 2006, when the bulk of this work was done, 10 climbers died on cell site projects, including four on jobs for AT&T within two months.

William “Bubba” Cotton, 43, was the first, crushed to death on March 10 when a rope snapped, dropping a 50-pound antenna on him. According to OSHA documents and court records, the accident occurred as two crews – one aloft and one on the ground – rushed to complete work on a tower in Talladega, Ala., before an upcoming NASCAR race. AT&T would not extend the deadline for the job despite a request from a crew leader, two workers testified in sworn depositions. (The company declined to comment on the case.)

The pressure ratcheted up again when AT&T became the exclusive carrier for the iPhone.

After the phone debuted in summer 2007, triggering a tsunami of data usage, customers began complaining about dropped calls and spotty service. According to a report in Wired, AT&T went to Apple, asking for help in limiting traffic to buy time for tower upgrades. Instead, Apple Chief Executive Steve Jobs explored switching to Verizon, the report said.

To prepare for the iPhone 3G’s introduction in summer 2008, AT&T poured billions of dollars into wireless capital expenditures. The push meant work on an unprecedented scale for tower climbers.

“It was nuts,” said Dan MacRae, a project manager who has worked on cell site projects for several turf vendors. “We were working in the field for 40 hours straight. They had crews in rain, sleet, snow.”

The building boom was accompanied by a string of accidents.

After two climbers died on AT&T jobs within a five-day period in April 2008, the carrier sent a letter to turf vendors calling for a construction stand down to discuss safety procedures and hold half-day courses to retrain workers.

But Guilford died just three and a half weeks after the work stoppage. Two more climbers died on AT&T jobs within the next four months.

AT&T would not answer questions about the stand down. In its statement, the carrier said that fatalities have decreased in the years since the stand down, aided by a safety initiative by OSHA and the tower industry.

Craig Lekutis – the founder of WirelessEstimator.com, a trade publication for the tower climbing industry – said the stand down turned out to be “more lip service” and not a long-term commitment.

Lekutis has tracked tower fatalities since 2004 and memorializes each lost climber on his website.

“Sadly, the major players know it’s happening and know that they are contributors to it,” he said, “but they don’t do anything.”

* * *

Tower-climbing fatalities have dropped considerably since the end of 2008.

Nine climbers died on cell site projects between 2009 and 2011, less than half as many as in the three previous years. There has been only one fatality on an AT&T job since 2009. Ethan “Little Britches” Hutchinson, 18, died in May 2010 after falling from a tower in Arkansas when his safety gear malfunctioned.

Some in the industry point to improved safety practices to explain the smaller death toll. Others say the recession cut into the volume of tower work and that, after finishing 3G upgrades, much of what carriers needed could be done on the ground.

With the next big push – building out 4G LTE networks – just getting underway in major markets, some veteran climbers worry that the fatality numbers will rise again.

“If not this year, another bad year is going to come,” said Reardon, the tower industry veteran. “It’s all about trying to do things faster and cheaper.”

The subcontracting system remains much as it was during the worst years, climbers say.

There are also many young men like Jay Guilford, with few prospects and no experience, willing to climb towers if it means a steady paycheck.

Years later, the horror of Guilford’s death remains fresh to Pierce, who was engaged to him at the time. She remembers receiving the phone call from his father as she arrived home from shopping for an upcoming trip to Disney World.

“I freaked out and screamed and just screamed and screamed,” she said.

Yet, about a year and a half later, when her current boyfriend was out of work, Pierce approached Phoenix of Tennessee to ask if he could apply to be a tower climber.

In retrospect, she regretted doing so, she said, but it was the only company she knew that had work. Ultimately, he found a job at Jack in the Box.

Guilford’s stepbrother, Anthony Acker, also sometimes works as a tower climber. The family tried to talk him out of returning to it about a year ago.

“He said, ‘Don’t worry about me, old man, I’m being careful,” said Gary Hart, Acker’s father and Guilford’s stepfather. “I just hope it all works out for him because I don’t want to go through all this again.”

Part 2: How OSHA has struggled to police this dangerous industry.

Travis Fox of PBS “Frontline,” Robin Respaut and Kirsten Berg of ProPublica and Habiba Nosheen contributed to this report.

PBS "Frontline" aired a film version of this story. Check local listings.