In addition to your iPhone's Built in Find my Phone feature, the Pixie App has a Find My Phone feature as well.
If you find that you have misplaced your iPhone (even if the phone battery has shut the phone off), launch the Pixie App on another compatible iOS device such as an iPad or a another iPhone (family, friends, etc).
Next login to your Pixie Account on that device, the App will detect that it is not on your usual device.
The App will then ask you if you are changing devices or if you are searching for your iPhone. Select Find My Phone.
Next the App will ask you to choose one of your other Pixiefied items (i.e. keys or wallet, etc) as the Primary Point for this search.
Then holding the selected Pixiefied item in your hand with the device you will then proceed to search for your missing iPhone.
You will complete an L-shape Search. One difference is you will have a button that will cause the phone point to make a beeping sound.
NOTE: If the option is available: It is recommended that you will have the Pixie App installed on another compatible iOS device a head of time, to enable you find your phone quicker when you need it.