Carriers are not currently using the spectrum that they gained in Auction 107, because of the issues that this article mentions. Their agreement with the FAA has given Verizon and AT&T the go-ahead to begin operations on this spectrum tomorrow (outside of existing FCC-approved test sites, which have been operating for months).

Which spectrum are you referring to that carriers have purchased and not deployed, if not 3.7–3.9 GHz?