How does Cortana wake up on Windows 10?

[Arizona Willie]

Waking up Cortana

On my Desktop when I say " hey Cortana " it wakes her up and then I can ask for something.
On my Lumia 640 XL Cortana does not seem to wake up to a voice prompt but she does after I click on the Microsoft icon.

Should she wake up like she does in the Desktop version of W10?
Or is this proper phone behavior?

 

[worldspy99]

Re: Waking up Cortana

The processor in Lumia 640XL does not support Hey Cortana function.

 

[Arizona Willie]

Re: Waking up Cortana

Thank you very much.

Now that I know it isn't malfunctioning I can quite worrying about it.