A behind the scenes look at 911 dispatch

  • Tuesday, February 11, 2014

911 call-takers answer 99 percent of emergency calls within 40 seconds at a rate of 99.7 percent, according to 2013 data. PROVIDED


In an emergency, callers to 911 do not care how the system works. They just want it to work.

But what goes into the Charleston County Consolidated Dispatch Center is remarkable. There are so many behind-the-scenes facets that the average person would never know the inner workings of the system.

However, Consolidated Dispatch Director Jim Lake gave a presentation to the Mount Pleasant Police/Legal/Judicial Committee last week, outlining the puzzle.

Some Basic Numbers

– 911 receives 1.2 million inbound and outbound calls annually

– There are 620,000 law, fire & medical incidents annually

– Consolidated dispatch has 132 Call-Takers, Dispatchers and Supervisors

– There are 28 Support, IT, Administrative and Managers

– The system boasts a $12 million operating budget

“In Charleston County, the 911 Consolidated Dispatch system processes approximately 3,500 phone calls per day,” Lake said.

This number includes 911, and seven-digit inbound and outbound calls.

Approximately 1,000 of those will be on a 911 line.

“Success is always met with challenge for 911,” he explained.

Case in point, cell phones accounted for 81 percent of all Charleston County 911 calls in 2013; however, cell phones do not provide an exact location. “That is why it is crucial that a caller tell the dispatcher exactly where they are when they call 911,” he said.

Wireless telephony is a “radio” signal and reception is subject to tower location and availability.

Tower sectors are assigned to particular PSAPs or public-safety access (or answering) points.

“For example, tower sectors on Daniel Island are assigned to the Berkeley County PSAP,” Lake said. “Wireless networks are sized for that provider’s customer base.”

There are safeguards built in so a 911 call gets priority, but there are times when a call is not sent correctly.

“We work with wireless providers to correct issues and most are minor,” said Lake.

“Some of the minor issues have been incorrect tower addresses, incorrect routing phone numbers, and outdated master address information.”

In one instance, a major issue was a wireless provider’s tower sector that was sending calls to another 911 center’s disconnected number.

Interesting to note is that for both wireline and wireless connections, a ring is two seconds and the silence is four seconds; so in 15 seconds, you should hear only three rings.

The line may ring 2-3 times in the caller’s ear before it rings once in the center. “In an emergency, this can seem like a long time for the caller,” Lake said.

Another Challenge for 911, he said, is abandoned 911 calls. This is when the caller hangs up prior to 911 answering the call. “Do not hang up if you call 911. If you hang up, a call-taker is required to call you back to verify whether your call was accidental or if you need our help,” he said.

“If you hang up and call back, two call-takers are tied up, one answering your call and the other calling you back. We answer 98.6% of all calls in 15 seconds or less.”

How does it work?

Lake said the call-taker talks only to the caller. That call-taker is simultaneously entering the incident information into a computer. The dispatcher then receives the incident information via computer and talks only to responders.

There is then two-way communication during the incident, between the call-taker and dispatcher via computer, phone and dialogue as last resort.

“We ask two questions before sending the information to a dispatcher who will send help,” Lake explained.

“We ask ‘What is the address of your emergency?’ and ‘Tell me exactly what happened.’ That information is sent electronically to the dispatcher so the call-taker never stops the questions.”

That means you won’t hear help being sent, but the call-taker will tell you, “My partner will be sending help.”

Calls are prioritized beginning with 911 calls.

The next priority in regards to answering are calls from another PSAP, emergency calls from alarm companies and Boeing come in third, and non-emergency administrative calls are prioritized last.

911 is provided to citizens to save a life, stop a crime, or report a fire.

Lake stressed that callers should precisely answer the call-taker’s questions and know where they are.

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