Even before cable news channels began to spread news of Minnesota's collapsed bridge catastrophe, engineers at T-Mobile knew something was up because they saw a vivid shift in mobile-phone calling patterns.
"They turned on the radio, heard the news, and initiated a conference call at once," said Peter Dobrow, a T-Mobile spokesman. "They had extra radios installed at two cell towers nearest the bridges to double capacity within two hours of the collapse."
Other cell phone operators also said they moved quickly to meet the unexpected spike in network traffic, but even so, many customers found their calls couldn't get through.
At moments of crisis, the performance of cellular phones gets attention because they become potential lifelines. In the wake of the bridge collapse on Wednesday evening, when some people on the scene couldn't get a connection, questions were raised about whether wireless providers are adequately prepared to handle unexpected call volumes.
"My frustration is that any tower on any network should have an emergency line, or else towers should work for all networks in emergencies," said Omar Thompson, 32, of St. Paul, Minn., a customer service worker in downtown Minneapolis. His first calls to reassure loved ones got out, he said, but were increasingly drowned out by automated messages:
"Current network not available."
Everyone from emergency officials to office workers complained last week that cell phone signals seemed blocked out by the deluge of calls from trapped commuters and panicked families watching the news Wednesday night. Rescue workers, in their first test of a new universal radio system, turned to their personal cell phones as backup. Authorities asked residents of the Twin Cities to stay off their cell phones, fearing the clogged lines would hamper rescue efforts.