Mobile phones are, without any doubt in my mind, one of the most liberating technologies to appear during the last 100 years. Unfortunately, that liberation comes at a price and the mobile networks are good are making big markups on the cost of calls.

Indeed, when Nokia announced it would add the mobile Skype client to the N97 handset, a number of networks demanded it was dropped or they would not stock the phone.

But now one UK mobile carrier, 3, has had a change of heart: it has announced that it will be offering totally free and unlimited Skype-to-Skype calls across its entire network and for all users.

In a company statement, a spokesperson said "we don't think you should have to pay for mobile phone calls anymore" adding "there are more than 400 million people in the world already using Skype."

Unfortunately, the service is only available to mobile customers in the UK, although they can call anyone anywhere on the planet free of charge provided they also have Skype access.

In order to get free mobile calls users will need a compatible handset and a 3 price plan. Aha, you say, so not free at all then? However, we understand that the 3 price plan requirement includes a Pay As You Go scheme.

Which means, apparently, that even if you are not a current customer of 3 you will be able to purchase a PAYG SIM card for just UKP £1.99 which will then allow any unlocked and compatible handset to make unlimited free calls and instant messages on Skype.

To start with that handset will need to be a Skype-branded 3 handset, which does mean an additional outlay of around UKP £50. Aha, so definitely not free then? But again, there is good news coming.

The initial offer, starting May 1st, will be expanded during the summer to include anyone with a compatible unlocked handset to take part. A handset compatibility checker is available online at 3 and seems to cover a pretty broad range of models.

So there you have it, mobile phone calls for free.