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I carry a cell phone for the same reason. There's a better chance AAA can find me in my suburban wilderness if I can call them on the phone.
Our dive shop is really pushing underwater cell phone cases to use I-phones for photography. They take decent pictures. I don't know if you can make a call with the case on (obviously you can't underwater...)
I'm a big fan of keeping cell phones handy & charged for distress calls. I nag my daughter about keeping a car charger in every vehicle, at least one wall charger each for trips if not more (chargers are so cheap in ebay, easy to pack, but so essential), and I even carry a spare phone on overnight trips in case one dies - had that happen once and needed one, even the pay phone I found didn't work. Mine is waterproof to 3 feet so wouldn't get killed by waves, if I had a dive case and didn't drop it when I needed it - but I wonder how good the tracking is at sea? My PLB floats and the tracking is very accurate.
I'm sure a PLB would work better in the US and our waters than in around Malaysia and Thailand - the failures of those two countries amaze me, but still - the plane's transponder was turned off. I do test my battery frequently and there is another test to ensure it actually is tracked by the satellites, plus it will work for 24 hours once activated. Just have to make sure it has a clear line to the sky, so if you're trapped in a wrecked car - at least stick it out of the window.
That's the one I rented for my last trip, and for more than once a year - buy it. I used two, heavy duty ties to double secure to a brass bolt clip. Just need to make sure it's closed well, clipped to your BC well, and over the edge of the boat before you roll. Replace the o-rings as indicated by inspection.
