The PlayStation-branded-mobile-phone-in-production rumour is an oldie and a goodie in the tech world, having been floating round cyberspace for what seems like years, but new, juicy info has apparently come to light on the topic.

Yet again, it's said that a PSP phone is being readied for launch, but what's interesting this time round is that Sony is said to be considering going it alone for the new device - ditching the Ericsson partnership for the phone.

Marketing Week reports that sources in Japan and Korea say Sony is working on "converting" the current PSP model into a phone, and that it could hit the shelves in time for Christmas 2009.

The current PSP can be used as a VoIP phone via its Wi-Fi connectivity but does not currently contain the technology to use cellular networks. This report makes it sound like the new device would be a PSP with full mobile connectivity, rather than a branded handset, like the just-launched F305.

Another industry source is quoted as saying the relationship between Sony and Sony Ericsson has become "frosty", that Sony has learned from its "strategic error" of giving its Walkman name to Sony Ericsson and that Sony would "never" give its PlayStation branding to the Sony Ericsson joint venture.