At the latest unveiling by Apple and mentioned in this post, they announced a new feature on the iPhone 6S and 6S Plus: you can have 'Hey Siri' enabled always rather than just when plugged into a power source. After downloading iOS 9 to my iPhone 6, I optimistically checked to see whether this feature was present in the settings, but to no avail - 'Hey Siri' is still restricted to when the device is plugged into a power source. Yet, surely this is a software-related matter rather than anything to do with the hardware. Why is the ability to have 'Hey Siri' enabled when not plugged into a power source restricted to the iPhone 6S and 6S Plus? Has Apple made any explanation of this, or is there some other evidence which accounts for this?

  • Welcome to Ask Different. Is there a practical problem you are trying to solve with this information or is it just face value - why did Apple do X?
    – bmike
    Sep 18, 2015 at 5:43
  • @bmike I'm just more curious than anything as to why Apple chose to do this and whether there is anything stopping this feature being enabled on older iPhones other than the limitations placed on it by iOS (i.e. any hardware differences) Sep 18, 2015 at 6:38
  • Incidentally, this is the same with the iPad Air 2 - it needs to be connected to an external power source for "Hey Siri" to work.
    – MrWhite
    Mar 4, 2016 at 9:48

4 Answers 4


It's just a matter of hardware. The M9 coprocessor in the iPhone 6s is efficient enough to keep the microphone listening all the time without murdering the battery, unlike the chips in older devices.

From the article your question links to:

With iPhone 6s, the device is constantly monitoring audio input in the background, a process made possible by the highly efficient M9 motion coprocessor embedded in Apple's new A9 system-on-chip.

  • Even if it was possible to do with the iPhone 6's co-processor, Apple wouldn't be motivated to retrofit it as they would lose a selling point advantage. Sep 18, 2015 at 12:17
  • 1
    I could've sworn that they told us that the iPhone 6 had a very efficient coprocessor too... Sep 19, 2015 at 10:19
  • 4
    @Simon_Weaver The iPhone 6 does have a very efficient motion co-processor, but it only monitors motion and not audio. The addition of audio capability is what's new in the iPhone 6s.
    – Mike Scott
    Sep 29, 2015 at 11:13

The best you can do is to use an external battery pack and then it will work even on the six :)

In addition I actually like the way it works now on an iPhone 6, because when I go to bed I just say 'hey Siri good night' and I can verify that my phone is plugged in if Siri replies

  • It's actually very cool-I was meaning one of those battery packs where it clips to the back of the phone as opposed to one with a cable. Of course before iOS 9 anybody could say hey Siri (it didn't used to compare with a recorded voice signature) so it was a little dangerous especially with a mischievous roommate. Sep 19, 2015 at 10:18

Strange.. This morning I said "hey siri" with the intention that my Apple Watch responds, when suddenly, my unplugged iPhone 6 responded! Yes, shocked as you guys. I tried it a number of times and it is working. 'Hey Siri" works on an unplugged iPhone6! Don't know if I'm experiencing a "bug" or what, but I'll take it!

  • Just set up Hey Siri on my iPhone and it's unplugged but I'm not getting anything- what iOS version are you running? Oct 14, 2015 at 22:28
  • This might be the reason why it worked: I've found out that if you say 'hey Siri' then unplug it, 'Hey Siri' works when the phone is unplugged. Doesn't work once you use the iPhone though! Oct 14, 2015 at 23:17

The feature IS AVAILABLE ON iPHONE 6 as well! (Provided you are running at least iOS 9.)

To enable, simply go to Settings > General > Siri and choose Allow Hey Siri.

  • 5
    Even with iOS 9, the feature requires an external power supply (as shown on the settings screen mentioned) to work on an iPhone 6.
    – nohillside
    Jan 26, 2016 at 20:40

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