May 15, 2014 -- Beginning today, the four major wireless carriers in the United States began voluntarily offering text-to-911 capability as an alternative to placing a voice call.
While the carriers are making the service available, it doesn't necessarily mean a 911 text message will get through to dispatchers in your area.
Here's what you need to know about how it works, where it works and when to use it.
Which Wireless Carriers Support It
AT&T, Sprint, T-Mobile and Verizon -- the big four wireless carriers in the United States -- support texting 911 in areas where dispatchers are equipped to receive messages, according to the Federal Communications Commission.
How it Works
In the number field enter 911 and in the body of text, state the emergency and location before pressing send.
Call centers that are set up to receive the messages field them several ways, Trey Forgety, director of government affairs at the National Emergency Number Association, told ABC News.
"If they are stuck with legacy technology or are planning for an upgrade to next generation 911, they can begin taking texts today using TTY [a service to help the hearing impaired]," he said.
Call centers with the resources to upgrade to a next-generation system can field the emergency text messages through a browser-based technology that connects a secure virtual network to the text provider, Forgety said.
It's important to note that 911 dispatchers set up to receive texts can't accept photos or video.
Where it Works and Doesn't Work
While the program could save lives in situations where it is dangerous or impossible to place a voice call, it's important to know that it's not yet implemented in every community.
Forgety expects many more towns to adopt the technology in the next six months, however, he predicts widespread implementation could take several years.
People who try texting 911 in an area it is not supported on one of the big four wireless carriers should receive a "bounce back" text message letting them know their message was unable to be sent, according to the FCC.
Text messages to 911 are treated like any other text message on the network, meaning delays are possible. Also, Forgety said it's crucial texters send their location so authorities can find them, otherwise "only coarse location info is available."
"It’s always preferable to make a voice call to 911," Forgety said. "Call if you can, text only if you can't."