not able to receive the station. The FCC sent extra personnel to Chicago, Philadelphia and New York City to deal with difficulties in those cities. WLS had received 1,735 calls just by the end of the day on June 12 (WBBM only received 600), and an estimated 5,000 calls in total by June 16. WLS-TV was just one station which needed to increase its signal strength or move its frequency to solve its problems, but a power increase required making sure no other stations were affected. WLS received a two-week experimental permit for a power increase late in June. WLS had also applied for a permit to construct a low-power fill-in digital translator station on UHF channel 32 (the former analog frequency of WFLD), but abandoned that plan (the channel 32 RF frequency has since been claimed by WMEU-CD). Eventually the FCC granted it a permit to transmit on a second frequency, UHF channel 44, formerly occupied by WSNS-TV; WLS announced the availability of that frequency on October 31, 2009. Throughout construction of the new maximized transmitting facilities at the Willis Tower, WLS operated both channels 7 and 44 from its auxiliary facilities at the John Hancock Center under an STA. WLS operated channel 7 as a fill-in translator with a power of 7 kW, and operating their full power operations on channel 44 with a power of 1 MW. Through the use of PSIP technology, both operating frequencies were re-mapped and displayed as virtual channel 7, which would cause some digital tuners to have two versions of virtual channels 7.1, 7.2 and 7.3, while tuning sequentially. In October 2012, WLS-TV completed construction from the Willis Tower and its operating channel 44 at the 1 million watt power level. The station continued its dual-frequency operations until 12:03 p.m. on March 18, 2013, when WLS-TV formally ceased operations on VHF channel 7, leaving UHF channel 44 as its permanent allotment. Since WLS-TV officially moved its full-power operations to channel 44, it is the only ABC-owned station to vacate its former analog allotment for its digital operations and the second ABC O&O to operate its full-power operations on the UHF band, after Fresno sister station KFSN-TV (which was forced onto UHF in 1961 when it was a CBS affiliate, as the FCC preferred Fresno to be a "UHF island"). On June 12, 2017, WLS-TV's parent company ABC Owned Television Stations and Univision