Spok Holdings, Inc., through its wholly owned subsidiary Spok, Inc., is engaged in healthcare communications. The Company offers a focused suite of unified clinical communication and collaboration solutions that include call center applications, clinical alerting and notifications, one-way and advanced two-way wireless messaging services, mobile communications, and public safety solutions. Its one-way and advanced two-way wireless messaging services, including information services, throughout the United States. It also offers voice mail, personalized greetings, message storage and retrieval, equipment, maintenance plans and/or equipment loss protection to both one-way and two-way messaging subscribers. It also develops, sells and supports enterprise-wide systems for hospitals and other organizations needing to automate, centralize and standardize clinical communications. It offers its services and products to three major market segments: healthcare, government, and large enterprise.