do not have to buy exclusive access licenses to use the band. Carriers can acquire optional non-renewable priority access licenses a size of census tract for three years. All network equipment using the band is managed by Spectrum Access System that assigns channels are regulates power levels of the network devices in order to share the spectrum in the most efficient manner. Carriers plan to use the band for indoor small cells in enterprises, hotels, airports, convention centers and stadiums and outdoor small cells serving large campuses, metro areas, downtown areas and suburban areas. Interference and limitations Professional wireless microphones used the 700 MHz band until 2010 when they were made illegal, but equipment still exists in use that may interfere with 3G and 4G technologies. Due to immediate adjacency to channel 51 lower 700 MHz A block license holders were prohibited to use it within channel 51 station service areas. Initially almost one third of US population was in the channel 51 exclusion zones. As of August 2016 T-Mobile US has cleared almost all exclusion zones by either subsidizing relocation of channel 51 stations or by obtaining a permission to use 700 A block while the stations still operate on channel 51. See also Detailed lists: Networks by technology: List of UMTS networks List of LTE networks List of 5G NR networks List of CDMA2000 networks Bands by technology: GSM frequency bands UMTS frequency bands LTE frequency bands 5G NR frequency bands CDMA frequency bands Other articles: Comparison of mobile phone standards 3GPP Roaming Dual-band Tri-band Quad-band 700 MHz wireless spectrum auction Microwave 4G 3GPP Long Term Evolution (LTE) Title 47 of the Code of Federal Regulations List of United States wireless communications service providers References External links Wireless Advisor FCC New bands considered by FCC Frequencies by Provider Radio resource management Spectrum auctions