Cortana is triggered on connecting mobile to subwoofer system using aux cable.

[Deepak]

Whenever I insert the aux cable into my phone's headphone jack, Cortana opens in listening mode. This happens both when phone is locked and unlocked. Any idea why this happens? It's a rare occurrence I guess.

 

[Maurizio Troso]

Whenever I insert the aux cable into my phone's headphone jack, Cortana opens in listening mode. This happens both when phone is locked and unlocked. Any idea why this happens? It's a rare occuring I guess.

Seems like your jack got 4 pins instead of 3. Or phone thinks it is like that
Check Gadget app

 

[Deepak]

Seems like your jack got 4 pins instead of 3. Or phone thinks it is like that
Check Gadget app

No, it's a 3 pin jack itself. My phone is a Lumia 830. What is check gadget app and what does it have to do with Cortana?

 

[Maurizio Troso]

No, it's a 3 pin jack itself. My phone is a Lumia 830. What is check gadget app and what does it have to do with Cortana?

I noticed when I plugged first time something, it opens Gadget asking me some settings (or nothing in case of earphones with mic and key controls)

Then, Cortana is controlled by earphone mic button too: short press, answering a call / pause music, long press opens Cortana in listening mode.
So I guess that jack causes a mic pin contact when plugged. Check carefully lenght and shape of both jacks, if they are identical.