Spok Holdings, Inc. is a provider of wireless messaging, mobile voice and data and unified communications solutions primarily in the United States, Europe, Australia, Asia, and the Middle East. It operates in two segments: wireless operations and the software operations. The company's Wireless segment provides one-way messaging, including numeric messaging services; two-way messaging services; voice mail; personalized greeting; message storage and retrieval; equipment loss and/or maintenance protection to both one-way and two-way messaging subscribers, as well as provides mobile voice and data services through third party providers. Its Software segment develops, sells, and supports enterprise-wide systems. Spok Holdings, Inc., formerly known as USA Mobility, Inc., is headquartered in Springfield, Virginia.