I took my 4S out to the park. I walked pretty close to a gazebo and the phone positioned me maybe just a few yards away. I stood just like 3-6 ft away from a spot where two sidewalks merged together, which was right where the phone positioned me. At home, my phone usually positions me somewhere near my house. I wonder how accurate the GPS is at my grandma's. Probably more accurate than my WiFi iPad or my iPod touch, which both sometimes positioned me on the hill adjacent to her house. She has WiFi, which could help. Is it true that GLONASS works indoors?