Just a day before the release of Season 4, Treyarch uploaded a video on their official Youtube channel titled "Season Four Studio Broadcast | Call of Duty: Black Ops Cold War." In this video, the members of Treyarch talked about the content coming in Season 4 of Warzone and Black Ops Cold War.
At first look, the video seems to be your regular Season 4 narrative video. But, as the subtitle of the video suggests, it is indeed a very "special broadcast."
As the members explain the content of Season 4, throughout the video, there are random codes with parts of it redacted. In one instance, if the last part of the code is redacted, then in the other, the first was redacted, and so on. It also has 'CONFIDENTIAL' written next to the redacted code.
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The first one appears during the conversation between John Rafacz (Director of Communications at Treyarch) and Miles Leslie (Creative Specialist at Treyarch) when Leslie explains the new features and content coming to Warzone.
The second code appears during a conversation between John Rafacz, Craig Houston (Lead Writer at Treyarch), and Kevin Drew (Expert Designer at Treyarch) during the Zombies section of the video.
Finally, the last one appears during a conversation between Craig Houston and Julie Nathanson (Voice Actor for Samantha Maxis).
When these codes are combined, it gives us a redeem code that can be used on the official Call of Duty website. The redeem code is SX4G-73D55-RNJ7.
Once redeemed, you will be rewarded with an exclusive calling card called 'Not Just A Theory.'
If you've made it this far, congratulations, you now own a unique and rare calling card that probably 90% of the players are not aware of.