Press voice command button on headset, say 'Find my phone', and let the app on the phone do the rest by triggering a flashing screen and/ or audible alarm tone at high volume. As long as the phone is within approximately 30 ft and the Bluetooth radio is turned on, the headset can initiate a connection with any phone it's been paired with (this part is already Baked).
This is the natural companion app to the Plantronics Find My Headset app, but should be compatible with any decent headset (Jawbone, Jabra, Motorola, Samsung, etc.)-- 21 Quest, Apr 02 2013 What if you lose the headset? What's wrong with the old fashioned Phone-it-up solution (other than you need another phone)-- Dub, Apr 02 2013 Well to put it quite simply, it requires another phone. Also, if you've put your phone into silent mode, you won't hear the ringer playing and, depending on your phone's settings, won't hear it vibrate, either. On Android phones, however, media volume is unaffected by Silent Mode, so sounds from things like games, GPS Navigation, YouTube, the music player, etc. still play at maximum volume. The app I'm proposing in this idea would be identified by the OS as a media source, thus the tone it plays would be heard even in Silent Mode.
If you lose the headset, you can locate it using the already- existing Find My Headset app mentioned in the post. The issue of losing both the headset and the phone at the same time is so unlikely to be encountered that I'm not going to bother anyone's time by Halfbaking a solution to it.-- 21 Quest, Apr 02 2013 Find My Iphone already does this from any other iPhone or any computer. It doesn't require Bluetooth, and doesn't matter if the phone ringer is turned off. It will always sound.-- Cedar Park, Apr 02 2013 Lookout Mobile Security does the same thing for Android, as do countless other apps (Norton Mobile Security, AVG for Android, WaveSecure, etc.), but they all require one thing: another phone or computer. This idea is intended for use when another phone is NOT available, or if you're outside the cellular coverage area, or if the only other phone available doesn't have internet service. Why's that so hard to understand?-- 21 Quest, Apr 02 2013 random, halfbakery