We're excited to announce that the #BlackOps3 Multiplayer Beta will begin on 8/19 starting on PS4. More information coming soon!— Treyarch Studios (@Treyarch) July 8, 2015
To access the beta you'll have to pre-order Black Ops 3 on PS4, although if you've already pre-ordered on PSN then you are set to go.
Everyone else, including those who pre-ordered from ShopTo, will need to redeem their Call of Duty: Black Ops 3 Beta code on the Black Ops 3 website. .
Call of Duty: Black Ops 3 arrives November 6.