47 CFR § 27.2 - Permissible communications.
(a) Miscellaneous wireless communications services. Except as provided in paragraph (b) or (d) of this section and subject to technical and other rules contained in this part, a licensee in the frequency bands specified in § 27.5 may provide any services for which its frequency bands are allocated, as set forth in the non-Federal Government column of the Table of Allocations in § 2.106 of this chapter (column 5).
(b) 775-776 MHz and 805-806 MHz bands. Operators in the 775-776 MHz and 805-806 MHz bands may not employ a cellular system architecture. A cellular system architecture is defined, for purposes of this part, as one that consists of many small areas or cells (segmented from a larger geographic service area), each of which uses its own base station, to enable frequencies to be reused at relatively short distances.
(c) Satellite DARS. Satellite digital audio radio service (DARS) may be provided using the 2310-2320 and 2345-2360 MHz bands. Satellite DARS service shall be provided in a manner consistent with part 25 of this chapter.
(d) 2000-2020 MHz and 2180-2200 MHz bands. Operators in the 2000-2020 MHz and 2180-2200 MHz bands may not provide the mobile-satellite service under the provisions of this part; rather, mobile-satellite service shall be provided in a manner consistent with part 25 of this chapter.
(e) 716-722 MHz and 722-728 MHz bands. The 716-722 and 722-728 MHz frequencies may not be used for uplink transmission and must be used only for downlink transmissions.