For those not familiar with Voice-over-IP (VoIP), it's essentially the ability to make phone calls over the Internet. Skype is the most popular consumer VoIP service.

PC-to-PC calls are free. It works just like MSN Messenger. You need the nickname of the person you want to call. You send them a request to authorise you; when they accept, they are added to your contacts and you can see when they are online. Click the name, click the green phone button, wait for them to answer and then you're connected.

You can also call conventional phones for a low flat fee, anywhere in the world through Skype Out.

And you can receive phone calls from the technologically challenged through Skype In. You can have up to 10 different phone numbers, each one in a different country, if you like, so that friends abroad can call you at local rates. Each phone number costs you £20/€30 per year.

Best of all, with a laptop and a broadband connection, you have free international phone calls while travelling too! A hotel Ethernet connection typically costs about £12/day. Some airport lounges have free wifi, while others charge around £6/hour. Compare that to the cost of either hotel phones or mobile calls, and the benefits are pretty obvious. I even have it installed on my PDA because the 3G data charges are cheaper than the cost of international calls.

Download for free from www.skype.com.