Safe patient care requires effective communication between health care providers. Hospitals currently use various communication strategies including alphanumeric pagers, smartphones, and Web-based communication tools. The utility and effectiveness of many such systems have not been tested. This ethnographic study of five teaching hospitals discusses the potential benefits and unintended effects of different communication systems. For instance, smartphones made it easier to respond to requests, but seemed to increase interruptions. An AHRQ WebM&M commentary illustrates a serious adverse event resulting from a smartphone interruption.