Jefferson Parish residents in need of emergency services can now contact 911 by texting, but the Sheriff’s Office says that should be considered a third option behind calling from a landline or a cellphone.

Sheriff Newell Normand said the text service, announced Thursday, is ideal for those with voice or hearing impairments, when a medical emergency renders someone incapable of speaking, or in situations of domestic violence or home invasion where a person cannot afford to be overheard speaking into a phone.

There are a few caveats, however.

The 911 system can automatically detect a caller’s location only if the call is coming from a landline, so text messages must include a location. Also, the text must explain the nature of the threat.

Pictures, videos and other attachments cannot be received, and the text cannot be sent to anyone else in the same message.

Normand said all of the major cellphone carriers support the service, though some of the smaller ones are still having issues with it. Any text that does not go through will trigger a message back to the sender stating that it was not successful.

Also, the service is not available to anyone whose cellphone is considered “roaming” — outside of its home area — by the carrier when the text is made.

Kenner and Gretna also are participating in the program, which includes fire and EMS service.

Maj. Ronnie Hoefeld, Jefferson’s 911 director, said Plaquemines Parish’s 911 system is the only other service in the New Orleans area that supports text messaging.

Follow Chad Calder on Twitter, @Chad_Calder.