That’s A Big Asterisk
Saturday 27 September 2014 • 6:54 PM
Via 9to5Mac
Apple’s website states that to trigger this function, the user should be “out running errands with your phone in your pocket.” As implied by that sentence, the device needs to be locked to start randomzing its MAC address. This was confirmed by the AirTight study, which found that about two minutes after the device’s screen was locked, it would start searching for a familiar Wi-Fi network using a random address. Every time the device wakes up and goes back to sleep, a new MAC address is generated.
There is another stipulation that must be met before this feature will kick in, however, and it’s one that most users aren’t going to meet. In order to start using randomized MAC addresses, location services must be disabled.
If that requirement hasn’t ruled out every iPhone user from taking advantage of this feature, a discovery in the second part of the study almost certainly will. During the first round of testing, the researchers at the AirTight blog had not used SIM cards in any of the phones being analyzed. When they put SIM cards into these units and activated a cellular data connection, they found that MAC address randomization was completely disabled no matter what other criteria were met.
Or you could just turn your phone off. Or better yet, not take it with you.