Please, watch where you're going, not who you're phoning. Thank you.
Seriously, I've already had two people nearly walk right into me today at work because they were so absorbed with tapping away on their phones, and the day's only half over. One lady almost got a door to the head because she didn't see I was slowly opening it from the other side. The second was weaving across a narrow walk path outside the office like a drunk driver, so I couldn't even take evasive maneuvers. She had two phones in her hands, so she was doubly occupied.