Apple is looking for clarification from the FCC as to exactly what applications will be included in its Text-to-911 initiative. Apple appears concerned about whether clients like its IP-based iMessaging application will be effected by the plan.

In a filing with the FCC, Apple suggested the commission make explicit that any proposed definition of covered applications includes only software that is "installed on a device that determines the user's location using technology that meets enhanced 911 requirements" and "independently enables the user to send text-based messages to and receive text-based messages from any valid North American Numbering Plan telephone number via the short message service protocol."

All four major U.S. carriers have agreed to accelerate the availability of text-to-911, with major deployments expected in 2013 and a commitment to nationwide availability by May 15, 2014. 

The FCC says text-to-911 will be a complement to, not a substitute for, voice calls to 911 services. 

Because a text-based 911 option will rollout in phases, the carriers will also deploy an automatic “bounce back” text message to notify consumers if their attempt to reach 911 via text message was unsuccessful because the service is not yet available in their area. Such a message would instruct the recipient to make a voice call to a 911 center.  

AT&T, Sprint, T-Mobile and Verizon Wireless have agreed to fully implement this “bounce back” capability across their networks by June 30, 2013.