Cross-game voice chat is not possible on the PlayStation 3 because of memory restrictions, Sony has revealed.

The PS3's RAM is gobbled up by the games it runs, which prevents the much-desired feature from being implemented, Sony Worldwide Studios president Shuhei Yoshida told Eurogamer.

"Once a game gets RAM we never give it back," he said. "It's not possible to retrofit something like that after the fact."

As revealed by Eurogamer yesterday, PS Vita, due out in Europe early next year, actually has more RAM than the PS3.

Vita has 512MB of RAM and 128MB of V-RAM, compared to the PS3's 256MB of system RAM and 256MB of video RAM. This enables features such as cross-game voice chat to run in the background while games are being played.

On the PS3, however, things are different.

"The game has to use its own memory to do [in-game voice chat]. There's always voice chat in the game. But it's a part of a game feature. It's not a part of an OS feature. That's the reason in terms of the ability to have voice chat across different games."

So, voice chat is better on Vita than PS3?

"We totally agree!" Yoshida replied.