Working on the 800-MHZ bandwith, Specialized Mobile Radio (known as SMR) began as a voice-only wireless communications service for private operations that required drivers and dispatchers, including delivery trucks and police offers. Radio towers connected dispatcher to their fleet, and access to a company's channel was limited to its owners. In the late 1990s, with the advent of demand for widespread wireless service and improved SMR technology, SMR has emerged a competitor to the cellular telephone industry.

Until recently, a SMR network was the domain of partially mobile businesses that needed to stay in touch. Beginning in the 1940s, businesses like taxi services held licenses to run their stations--be it mobile, portable, or control--through an exclusive channel paired with a specific SMR base station. By the 1990s in big cities, the demand for SMR became so great that the airwaves were nearly filled. In 1992, Motorola, then...