That's interesting! I have been experiencing a problem with my iPhone7 making random calls (though not FaceTime calls) mainly to numbers that are in my contact list, and at least one to a number not in my contact list (the latter just happened today). Perhaps it was a number from a robocaller in my recent call list.
I have had Siri disabled in my settings for over a year, so was getting frustrated with these outbound calls being triggered and having to quickly disconnect the calls before they were answered. Some people answered before I could terminate the call and I had to think fast as to why I was calling them, when it may have been more than a year or two since I've talked to them!
Anyway, after today's unintended call to an area code and number I'm not familiar with occurred (which went to an out-of-service recording), I decided to figure out what was causing the problem. Something they all had in common was that I was using my AirPods at the time, and the calls seemed to be triggering if I was readjusting the fit of AirPod, or if I accidentally double-tapped the AirPod. My wife and I share the AirPods when we're out doing our daily 5 mile walks and if one or the other of us accidentally tapped the AirPod they're wearing, the phone would go into the Voice Control mode. Kind of surprising when it happens, especially since I was certain that I had Siri completely disabled on the iPhone.
So it was clear that doing a double-tap of the AirPod will initiate the Voice Control feature on the iPhone, even if you have the Siri option disabled/turned off in Settings. The Voice Control screen presents a number of options, including playing a playlist, pausing a song or program, dialing (a number), making a phone call, or making a FaceTime call, plus several other options. Next, I did something I hadn't done before: I read the Apple Support page "Learn more about your AirPods with charging case." This page is where I learned how to control the double tap feature for my AirPods, including how to disable Siri from making unintentional phone calls if I happened to double tap one of my AirPods.
As instructed in the link above, I went into the iPhone's Settings screen, and located my AirPods under My Devices. At this point, I put the AirPods in my ears to enable me to get to the options screen for them, i.e., they need to be in "Connected" status. Clicking on the connected AirPods device takes you to the next screen where you choose what happens when you double-tap on the AirPod. You can set what happens on the Left AirPod separately from what happens on the Right AirPod. Both my left and right were set for "Siri", thus Siri was enabled with the AirPods, even though I had disabled it from the iPhone. I reset both the left and right AirPod options to "Play/Pause" and voila, no more Siri making unintended outbound calls! The other double-tap options for the L & R AirPods are "Next Track", "Previous Track", and "Off". I believe that the out-of-the-box default option for AirPods is for Siri to be enabled.
Hopefully this info will help other AirPod users who may have experienced unintentional out calling from their iPhones.
