Sony said on Wednesday it is delaying the planned introduction in late January of a Skype Web phone service for PlayStation Portable (PSP) users in Japan due to technical problems.

Sony's game unit said earlier this month it would start offering Skype software for downloading onto the latest PSP model, enabling PSP users to make free Web-based phone calls to other PSP users and to users of PCs equipped with Skype software.

However, the game unit said on Wednesday a microphone it planned to start selling in Japan for the new service did not meet Skype specifications, forcing the delay.

The Skype service on the PSP will be starting later this month overseas as planned, since Sony is offering PSP headsets that meet Skype specifications outside Japan.

The game unit said it was unclear when the service would become available in Japan.