In an instant, the business-as-usual monotone voices of dispatchers can become wild cries of firefighters or officers shouting "flames showing" or "shots fired."
Jeff Hooper has been a scanner fan for 25 years, but the most memorable event he monitored happened the evening of Jan. 10, when firefighters in Haltom City pulled a woman and her three grandchildren, including an infant, from a house fire.
Hooper said that the firefighters' voices were muffled by their face masks, but that their distress was clear, even over the scanner, as they brought out each victim. All four victims died.
"I will never forget that," Hooper said.
It was created in 2010 by then-high school student John Burgdorf of Arlington. As of Friday, the network had more than 62,258 "likes" on Facebook and almost 15,000 Twitter followers.