Pagers have been a mainstay for urgent clinician–clinician communication for many decades. Increasingly physicians are using a variety of electronic devices, including smartphones and Web-based technologies. This systematic review identified 16 articles that studied different technologies for urgent clinician communication. Each strategy had potential advantages and pitfalls. For example, smartphones are associated with decreased transmission time compared to pagers, but they also result in more clinician interruptions. There is very little evidence linking any specific communication method with benefits for patient care. Future study could more robustly explore which forms of communication are best for clinicians and patients. A prior AHRQ WebM&M commentary describes a case of serious patient harm related to a smartphone interruption.