3 has raised the stakes with its X-Series offer by giving subscribers unlimited internet calls for £5 a month.

The X-Series Silver deal will allow subscribers to call any PC-based Skype users as well as fellow X-Series users from their 3 mobiles. The deal also includes unlimited instant messaging.

For £10, a user can add access to streaming media from a home PC plus access to home TV using a Slingbox to transfer content over the internet. The X-Series Gold deal gives unlimited access to home TV via a Slingbox and home PC files with Orb. For £10 a month customers can watch home TV through a Slingbox or access PC files on the move.

Both deals require six-month sign-ups. A further deal, which includes a subsidised Slingbox for £99 (to channel home TV over the internet), requires a 12-month contract.

The bundle effectively offers flat rate calls to a group, a deal that could prove compelling for some businesses, particularly those with staff overseas.

The offer launches with just two handsets that support the full range of services: the Sony Ericsson W950i and the Nokia N73.

Both of the X-Series deals will be subject to a fair use policy. 3 has defined this policy as 5,000 Skype-to-Skype call minutes per month, 10,000 Windows Live Messenger messages per month, 1GB per month for browsing and 80 hours per month of access for Orb and Slingbox content.