47 CFR 95.811 - License requirements.
(b) Each CTS where the antenna does not exceed 6.1 meters (20 feet) above ground or an existing structure (other than an antenna structure) and is outside the vicinity of certain receiving locations (see § 1.924 of this chapter) is authorized under the 218-219 MHz System license. All other CTS must be individually licensed.
(c) All CTSs not meeting the licensing criteria under paragraph (b) of this section are authorized under the 218-219 MHz Service system license.
(d) Each component RTU in a 218-219 MHz Service system is authorized under the system license or if associated with an individually licensed CTS, under that CTS license.
(e) Each CTS (regardless of whether it is individually licensed) and each RTU must be in compliance with the Commission's environmental rules (see part 1, subpart I of this chapter) and the Commission's rules pertaining to the construction, marking and lighting of antenna structures (see part 17 of this chapter).