The United States Federal Communications Commission on Friday said that all text message providers must support Text-to-911 — not just some of the SMS services you might already be using.

AT&T, T-Mobile, Verizon and Sprint already support text-to-911, which went into effect in May 2014, but the FCC wants other smaller carriers an third-party "IP-based text application providers," like iMessage, to add support by the end of the year. "After that time, if a 911 call center requests text-to-911, text messaging providers will have six months to deploy the service in that area," the FCC said. While it's being mandated, there still aren't very many 911 call centers that actually support text-to-911.

Although text-to-911 availability is currently limited, it is rapidly expanding. More than one hundred 911 call centers serving portions of 16 states and two entire states (Vermont and Maine) are now accepting emergency texts, and there are already reports of lives saved. To help protect consumers as text-to-911 is deployed, the Commission previously adopted rules requiring text messaging providers to send an automatic "bounce-back" text message to consumers who try to text 911 where the service is not available.

"Text-to-911 is a complement to, not a substitute for, existing voice-based 911 service, so consumers should make a voice call to contact 911 during an emergency when possible; consumers who are deaf, hard of hearing, or speech disabled should use relay services or other existing methods to contact 911 if text-to-911 is unavailable," the FCC said in a statement, highlighting the benefits of text-to-911 for deaf users.