Dreaming here, but I wonder if someone from the Periscope team could go around mid-Market/Tenderloin and try and get people to do exactly what you're describing

Dreaming here, but I wonder if someone from the Periscope team could go around mid-Market/Tenderloin and try and get people to do exactly what you're describing. Spread the word: "Need to call 911? Use Periscope to educate the 911 dispatcher about the problem." Visit shelters, offices, etc. in a 1/2-mile radius or something and ask people to do it. Of course you then get into an issue where the 911 dispatcher is not the person who would actually know the street-level specifics, but you're right that there would seemingly be countless benefits. Tackle it from both sides, maybe, and talk to the city while you're at it (as slow as things move, the only way to actually change things is to start).