Microsoft is in ongoing discussions with Sony about how cross-play could be implemented for the Xbox One and PlayStation 4, allowing gamers from the two platforms to interact in multiplayer games. Aaron Greenberg, Xbox’s head of marketing, confirmed Microsoft is speaking with Sony.

We’re talking to Sony [about cross-play], we do partner with them on Minecraft and of course we would like to enable them to be part of that; one community, to unite gamers,
– Greenberg

Sony has largely avoided enabling cross-play functionality thus far. It’s only available between the PS4 and PC for a couple titles. Sony has fully prevented people from playing with Xbox One and Nintendo Switch users.