I find myself working on ladders and the roof solo from time to time. I carry an in-reach Locater beacon with me so that if I should fall, I can summon help. Basically a hikers version of the "help I have fallen and cannot get up" system. Hopefully I would be able to push the button should I be injured to the point where I could not get up/go for help.
discover.garmin.com
I carry one in the woods with me. Every Monday I send an email to myself, then send a return message to the unit. The message to my email includes a map of where it was sent from. For my purposes that doesn't always work that well... if it doesn't have a clear sky it may not work. That may not be the case if sending an SOS.
An interesting tidbit; the first person to send for help with one was a hunter from Pennsylvania who had canoed several miles up a river in New York and was stranded in a massive late fall snowstorm. It took them a while to find him and the helicopter didn't have fuel enough to haul his gear out. He had to leave everything there including an expensive, custom made canoe.. A couple of weeks later he parked about 5 miles away and hiked in to his campsite; only to find his canoe had been stolen. He spent the night in his tent, and activated the beacon again. The SAR teams didn't seem to mind the first time as that's what they are there for. They weren't very happy about the second time, however.
