This research took place over several months, anchored by a series of video calls in which researchers took turns sharing their screens to display visual explorations of data. Researchers from Internet Outage Detection and Analysis (IODA) of the Center for Applied Internet Data Analysis (CAIDA), Open Observatory of Network Interference (OONI), RIPE Network Coordination Center (RIPE NCC), Measurement Lab (M-Lab), Internews and Access Now joined a collaborative effort in 2020 to compare existing data on outages with Mozilla’s dataset. the time it takes to perform a TLS handshake). In order to first assess the reliability of a dataset designed for this purpose, we invited a group of external researchers to query a dataset of aggregated signals that could be indicative of outages (e.g. Mozilla’s aggregate data for detecting outages is not publicly shared although it contains no personally identifiable information. But researchers and journalists can usually only hone in on the exact nature of an outage by combining data from multiple sources. Several large technology companies, including Google and Cloudflare, publicly share data about outages of consumer-facing products in different ways. At the country or city level, this can provide a corroborative signal of whether an outage or intentional shutdown occurred. When large numbers of Firefox users experience connection failures for any reason, this produces an anomaly in the recorded telemetry data. Documenting outages helps internet access defenders understand when and where they took place even when authorities or service providers may deny them. Whenever an internet connection is cut in a country or city, the safety and security of millions of people may be at stake.