I'm interested in this functionality as I mostly ride alone and often in remote areas. Several times I've clipped something (rock or branch) on very narrow "balcony" singletracks running along the side of a very steep ridge and been thrown down the drop, generally ending upside down and tangled in the bike amongst the down-slope tree branches that saved a further fall.Both phones call my emergency contact if they detect a crash. The one on the handlebar has tried to call them once when I dropped off a big ledge, but as it was visible. I stopped the call.
I always carry my phone with me and generally in my small backpack (to avoid damage in the event of incidents like this). But as a friend pointed out to me, if I had seriously injured myself or was simply unable to extract myself from the trees I wouldn't be able to access the phone in my pack. Carrying it in a shorts pocket would make it more accessible but more exposed to crash damage.
I looked into Garmin watches where some models have this kind of "crash detection" feature, but the feedback seems to be that they aren't too reliable - often giving false positives or not reacting to a genuine crash.
Is your crash detection function an App on your phone, or a feature of the phone itself? iPhone or Android? Is it reliable "enough" and would you recommend it? Thx.