Every day, cellphones make more than 400,000 calls to 911. In fact, cellphones account for more than two-thirds of all calls to first responders, according to the Federal Communications Commission. The spread of cellphones has made it a lot easier to call for help from the side of the road or in other places not served by landline telephones. But what if, instead of making a call, you try to send 911 a text message? Chances are it will get lost in an electronic purgatory, never to be seen by an actual human.

Wireless companies are moving quickly to change that. By mid-May, the nation's four biggest carriers are expected to roll out text-to-911 service across the country — the result of a voluntary agreement struck in 2012. On Thursday, the Federal Communications Commission voted unanimously to start studying text-to-911 in greater depth and to develop industry-wide standards for such a service.

Some states have already begun experimenting with the technology. Ninety percent of Vermonters, for example, can text and converse with a dispatcher by SMS. The pilot project has effectively expanded 911 access to people with disabilities — such as those who are hard of hearing — and made it safer to contact emergency services at times when speaking out loud might be too dangerous, such as during an active shooter situation.

Coordinating 911 communications is a complex business. It isn't enough for wireless carriers to support text-to-911; those on the receiving end also have to support the feature. And on Thursday, FCC Chairman Tom Wheeler slapped dispatchers on the wrist for failing to "get with the program."

"The response from PSAPs [public safety answering points] has been underwhelming," Wheeler said. "The industry has done its part; the FCC has done its part. Now it's time for the PSAPs to do their part."

Under the FCC's proposal, all wireless carriers — not just the big four — would be expected to implement text-to-911 by the end of the year.