Inconsiderate cell phone use is one of the most frequent causes of rudeness in the digital age, says Senning. If your phone rings, think about where you are. "Before making a call in public, ask yourself if it might be annoying to anyone else," he writes. "If it would be, step aside first." But being careful about when and where to use your phone also has a flip side. "If you are waiting for a call to coordinate meeting up with people, be sure your phone is on, powered up, and gets a signal," Senning writes. "It's so annoying to try to reach someone who is not answering his phone when he should be."