Netflix runs six cellular sites in its mobile device lab in California, Variety reported.
This lets the company test its services under a variety of Wi-Fi and mobile data conditions.
Netflix also uses Faraday-cage-like boxes which filter out external interference and prevent the cellular test sites from interfering with phone reception in the rest of the Netflix campus.
Netflix’s testing follows the recently re-encoding of its entire library, on a per-scene basis, to optimise videos for mobile viewing.
It told Variety it segments videos into shots for analysis, which allows them to stream an action scene at a higher bit rate than scenes with less motion – saving a lot of data.
The result is that a few years ago, 10 hours of Netflix video was about 4GB of mobile data – now users get up to 26 hours of video for the same amount.