SMR (Specialized Mobile Radio)

  Specialized Mobile Radio, also known as Trunked Radio System, Public Access Mobile Radio, Trunking, and finally Commercial Trunked Radio.

  A Definition of Commercial Trunked Radio:  Wireless radio communications systems which employ either conventional or trunking technology.
Historically, these systems have provided one-to-many and many-to-one voice communications service - also known as mobile dispatch services. These systems are operated by commercial entities, otherwise known as service providers, that are in the   business to resell their services to other entities for a profit.