On January 31, the FTC submitted a comment letter in response to the FCC’s request for input on its November adoption of rules allowing phone companies to proactively block illegal robocalls originating from certain types of phone numbers. (See previous InfoBytes coverage here.) Calling the development of a call-blocking, call-filtering solution to protect consumers from illegal and unwanted calls long overdue, the FTC offered support for efforts to encourage providers who block calls to “identify and quickly rectify any erroneous blocking.” However, FTC staff claimed that, based on the current record, it is unclear whether there exists “a need to require a formal challenge mechanism for errors resulting from provider-based call blocking authorized by this Report and Order.” The FTC noted that a formal challenge process is not necessary because, among other things, the FCC already cautions providers about wrongfully blocking unallocated or unassigned numbers and “warns providers that erroneous blocking may lead to liability for violating call completion rules.” Additionally, the FTC agreed with concerns raised by a telecom association that “white lists,” which contain numbers that should not be blocked, pose “substantial security risks” if the lists “fall into the hands of even a single robocaller” because they might serve as the “‘de facto master key’ that would provide robocallers with the ability to override all of the efforts painstakingly developed to thwart them.”