MONTPELIER (AP) - The head of the organization that oversees Vermont's 911 emergency telephone system says the state is the first in the country where customers of the four major wireless carriers can send text messages to 911.

David Tucker says that as of Monday T-Mobile customers in Vermont are now able to text 911.

Verizon, AT&T and Sprint began the service earlier.

Tucker says Verizon set up a test system in 2012 and kept using it after the test proved successful.

He says there have been a number of cases where people have successfully sought and received help by texting 911.

Tucker emphasizes that wireless customers should only use the texting option only when calling 911 is not possible.