Apple has invented a more discreet way to call emergency services with a touch, aimed at helping users evade potential attackers.

A patent granted on Tuesday depicted technology that would sense the “manner” in which a finger touched the iPhone screen to trigger a 911 call. For example, the phone might look for a particular sequence of fingers, the level of force, a gesture (pinching or swiping), or a certain cadence of taps to the screen, the filing says.

When the “panic command” is activated, the phone would provide the users’ location to responders, and could also livestream audio or video from the iPhone. The system could also be used to activate other types of mobile command, according to the patent.

Although many phones allow emergency calls from the locked screen, existing options activate a call screen that could be “readily apparent to someone watching,” the patent application says. With the patented technology, if an attacker requires the user to unlock or use the phone, the user can appear to be complying with their attacker while secretly calling 911. Users could use unusual combinations, like “pinky-ring-pinky,” to look like they are unlocking their phone while also calling the police, the patent said.

Unfortunately, this technology isn’t available yet, and may never be. Not all patented technologies are put to use — indeed, the filing mentions headphone jacks, which Apple has phased out. That indicates that this patent, which was applied for in 2013, may be from an earlier vision of the iPhone. Plus, rumor has it that upcoming iPhones may have finicky fingerprint sensors but rely on facial recognition.

Apple did not immediately respond to a request for comment, and rarely acknowledges new product features until they are released.

The feature would build on innovations such as Apple’s new SOS feature, recently added to the Apple Watch to support better emergency calling. (And like SOS, the fingerprint feature would have to deal with the occasional accidental triggers, something Apple has presumably worked out with Touch ID payments.)

Still, it’s a feature that’s certainly in demand. One woman’s story went viral after she used an online order to Pizza Hut to reveal that she was being held at knifepoint by her boyfriend.