or explanation as he may deem appropriate. (b) Wire-line communication common carriers may be authorized to establish land mobile radio facilities under this part of the rules for the purpose of providing communication facilities for their own use incident to construction and maintenance of public communication facilities: Provided however, That the use of the authorized facilities on such frequencies shall be on a secondary basis and subject to use by public subscribers at any time when required for the rendition of public communication service. § 21.512 Priorities for service to subscrib ers. (a) Subscriptions to mobile telephone service shall be afforded in the following order of precedence and in chronological order of filing of request for service within each of the following customer categories: (1) Category 1: Public safety and health. Official Federal, State, county and municipal government agencies protecting the public safety and health; private organizations and persons engaged primarily in protecting the public safety and health such as physicians, hospitals, ambulance services, volunteer fire departments, American Red Cross, licensed protective patrols and armored cars and similar agencies. (2) Category 2: Public service. Contract carriers, common carriers, and public utilities (exclusive of taxicab and delivery service), for communications other than correspondence of the general public. (3) Category 3: Quasi public service. Emergency repair organizations, not included in Category 1, protecting health and property; press associations, newspapers and broadcasting stations. (4) Category 4: Physically handicapped. Persons who because of physical handicaps, operate specifically equipped vehicles and are unable to leave such vehicles without assistance. (5) Category 5: Industrial. Gas or oil producing or drilling operators; producers and distributors of fuel and lumber and other construction materials and equipment; food processing, distribution and storage organizations; producers of substantial quantities of food; business concerns engaged in construction of housing and industrial or public works; taxicabs and livery service. (6) Category 6: Traveling public. Trains and watercraft where service is made available to passengers. (7) Category 7: All others. (b) After initial establishment of service in accordance with the table of priorities in paragraph (a) of this section when facilities in a given area are insufficient to furnish service to all who desire mobile radiotelephone service, applications for new or additional mobile units shall be ranked within the categories in order of date of filing and service shall be afforded such applicants as facilities become available, in descending order of precedence. § 21.513 Location of message center. Within the service area encompassed by the field strength contour of each base station as defined in § 21.504, there shall be at least one message center so located that the major portion of subscribers' local exchange landline telephone calls, which originate or terminate in such area in conjunction with messages transmitted or received by said station, cost no more per call than the local message single unit rate. In cases where the control point of a base station is not so located, a public foreign exchange telephone circuit shall be provided to afford service so that a radio service subscriber may communicate between such points at a cost per call not in excess of the local message single unit rate. § 21.514 Responsibility for operational control and maintenance of mobile units. (a) The licensee of a base station in this service shall be responsible for exercising effective operational control over all mobile units with which it communicates. The proper installation and maintenance of such mobile units shall be the responsibility of the respective licensees thereof. (b) A mobile unit normally associated with and licensed to a specified base station will be deemed, when communicating with a different base station pursuant to legally effective tariff provisions, to be temporarily associated with and licensed to such different base station and the licensee of such different base station shall, for such temporary period, assume the same licensee responsibility for such mobile unit as if such unit were regularly licensed to it. § 21.515 Control points, dispatch points and dispatch stations. (a) Dispatch stations, other than those installed pursuant to § 21.519(a), may be installed only with specific authorization from the Commission. Upon removal of a specifically licensed dispatch station, the licensee must within 30 days thereafter submit to the Commission in Washington, D.C., the dispatch station license for cancellation. Dispatch points may be installed or removed without authorization. Dispatch point circuit facilities shall be installed in conformance with the requirements of paragraph (c)(2) of this section. (b) To insure the maintenance of station control, means shall be provided whereby each dispatch station and each dispatch point is maintained under continuous effective operational supervision of one or more control points. (c) At each control point for a base station or fixed station in this service, the following facilities will be installed: (1) Equipment to permit the responsible radio operator to monitor aurally at such intervals as may be necessary to insure proper operation of the integrated communication system, all transmissions originating at dispatch points under his supervision and at stations with which the base station communicates. (2) Facilities which will permit the responsible radio operator either to disconnect immediately the dispatch point circuits from the transmitter or immediately to render the transmitter inoperative from any dispatch point associated therewith. NOTE: Reference should be made to §§ 21.118 and 21.518 for additional control point requirements and also to § 21.205 concerning operator requirements. [28 FR 13002, Dec. 5, 1963, as amended at 29 FR 11362, Aug. 6, 1964] § 21.516 Additional showing required with application for assignment of addition. al channel or channels. An application requesting the assignment of an additional channel or channels at an existing Domestic Public Land Mobile radio station (other than control, dispatch or repeater), in addition to the information required by other sections of the rules, shall include a showing of the following: (a) The number of mobile units for which orders for service are being held. (b) Data showing the actual traffic loading on each channel assignment of the present radio systems during the busiest 12-hour periods on 3 days (within a 7-day period) having normal message traffic not more than 60 days prior to the date of filing. This information should be reported separately for each of the 3 days selected, which should be identified by dates, and should disclose the following: (1) The number of mobile units using the service during each of the days specified. (2) The number of calls completed each hour. (3) For systems that provide message relay service, (i) the number of calls held, (ii) the total holding time, and (iii) the maximum holding time for a call, due to busy radio circuit conditions during each hour; or, for systems that do not provide message relay service, the total number of minutes that the channel (base and mobile) was utilized for transmissions between the base station and land mobile units during each hour. (4) For systems that provide one-way signaling as a primary service, (i) the number of mobile receivers in operation during the study period, (ii) the number of calls held, (iii) the total holding time; or for systems that do not provide message relay service, (iv) the total number of minutes the chanris utilized for transmission between the base station and the mobile receiver during each hour. (5) Such other additional information which may more accurately re flect channel loading, and any further information which may be applicable and pertinent to the application. [30 FR 2448, Feb. 25, 1965, as amended at 35 FR 10446, June 26, 1970] § 21.517 Use of base station as a repeater station. On its regularly assigned frequency, a base station may be used to perform the added functions of a repeater station when means are provided whereby the licensee of the radio system is able to turn the base station on and off at will from its control point irrespective of the transmissions of subscriber units on the mobile station frequency associated therewith. § 21.518 Use of mobile station frequency for control station. Upon proper application to the Commission for a construction permit to install a control station, a base station applicant or licensee may be authorized to operate its base station via a control station using the mobile station frequency paired therewith. In order to ensure retention of essential operational control of the radio system by its licensee, it is expected that this method of operation will not be installed where the signals from subscriber operated units are able to override the functions of the control path between the control and base station, or where such operation will cause harmful interference to another radio system. The control station shall be provided with coded signals whose transmission will enable the control station to shut down and reactivate the base station at will, irrespective of the transmissions of subscriber units associated therewith. Additional coded signals may be employed by the control station for selective signaling of subscriber units or for performing essential functions at the base station, e.g., controlling aeronautical obstruction marking lights on the base station antenna tower. The coded signals used by control stations for shut down and reactivation of the base station, or for any other essential control functions (other than selective signaling incidental to establishment of subscriber communications) connected therewith, shall consist of two or more sequen tially transmitted tones whose combined duration shall not exceed one second. Use of tone modulation for selective signaling to and from subscriber radio installations is not required; however, when tone modulation is used for this purpose, the aforementioned limitation on the combined duration of tones is not applicable. Radio installations in the premises of, or in vehicles of, subscribers are not permitted to be equipped with code signaling devices (other than for signaling incidental to establishment of subscriber communications) whereby the user would be able to reactivate the base station after the radio system has been shut down by the licensee. Applications for authority to operate a control station upon the mobile station frequency shall be supported by complete engineering information disclosing, among other things, all particulars of the code signaling system which is to be employed. § 21.519 Use of mobile station frequency for dispatch stations. A base station licensee may be authorized to install, for a mobile station subscriber or a group of mobile station subscribers, a dispatch station using the mobile station frequency paired with the associated base station frequency. Authorization for the establishment and operation of any dispatch station will be on the express condition that such station will not cause harmful interference to the mobile or rural radio services and will not inhibit use by the mobile radio service of the frequencies assigned to the dispatch station or degrade the mobile communication service rendered by the base station. No dispatch station shall be installed at any site or under conditions whereby it will be capable of overriding the control functions of a control station using the same frequency. (a) A licensee may install a dispatch station without authorization for the specific location if the antenna height employed at any such location does not exceed the criteria set forth in § 17.7 of this chapter, the rated power output of the transmitter does not exceed 10 watts and each such installation otherwise complies with the re quirements of §§ 21.107, 21.108, 21.110, 21.506, 21.520 and all other pertinent provisions of this part. The number of such dispatch station installations shall not exceed the number stated on the base station license. The operation of any such installation shall be subject to termination by the Commission without a hearing upon notice to the licensee. (b) Any proposal for the installation of a dispatch station which does not comply with the limitations and requirements of paragraph (a) of this section shall be submitted to the Commission upon proper application (FCC Form 401) for a construction permit. [29 FR 11362, Aug. 6, 1964, as amended at 36 FR 2562, Feb. 6, 1971] § 21.520 Notification of operation of dispatch station without specific authorization. (a) The licensee of a base station who proposes to establish a dispatch station pursuant to the provisions of § 21.510(a) shall notify the Commission at Washington, D.C., 20554, and its Engineer in Charge of the radio district wherein operation is to be conducted, at least 2 days prior to the installation of the facalities. This notification shall include: (1) The name(s) and address(es) of subscriber(s) and the number of mobile stations assigned to each subscriber. (2) A description of the transmitting location, including the geographic coordinates to the nearest second of latitude and longitude, and also by conventional reference to street number, landmark, etc. (3) The name of the manufacturer, type number and rated power output of transmitter to be installed. (4) The transmitting antenna make, model number and power gain in decibels with respect to a reference halfwave dipole antenna. (5) The overall height of the transmitting antenna structure in feet above ground and above mean sea level. (6) The location of the transmitter control point. (7) The exact frequency of frequencies to be used. (8) The identity and location of the base station through which it will communicate. (9) The commencement date of operation. (b) A copy of the foregoing notification shall be posted with the base station license. (c) Upon termination of the operation of a dispatch station for which notification was given pursuant to paragraph (a) of this section or, in the event any of the facts alleged in such notification will be changed, written notice thereof shall be given to the Commission and its Engineer in Charge, at least 2 days prior to the execution of the change. [29 FR 11362, Aug. 6, 1964, as amended at 35 FR 10446, June 26, 1970] § 21.521 Nationwide plan for assignment of frequencies to land mobile systems rendering communication service to airborne stations. (a) The following frequency pairs designated by the working channel numbers indicated below are designated for assignment only to land mobile radio systems, which are interconnected to the nationwide public landline message telephone system and afford communication service to airborne sta tions: |