The seeds of VoIP were sown about 10 years ago, when hobbyists developed software that could convert voice into data and back again. The slow speed of modems in the mid-Nineties meant that anyone trying out VoIP would be engaged in a fruitless exchange, with long silences punctuated by both people talking at once. But it remained a toy with potential, and by 1997 VoIP was carrying 7.5 million minutes of international voice traffic.

Since then the figure has increased enormously, thanks to broadband. Anyone with a speedy internet connection, a computer with a soundcard and some VoIP software can talk to other users of that same piece of software - for example, Skype - for free. But most of us need our telephone service to be able to call numbers on the traditional telephone network, so gateways have been built to enable VoIP users to dial the real world, for a small charge. So it's cheap - but is it cheerful? One of the continuing problems is the need, with some VoIP providers, for you to sport a headset with a built-in microphone in order to suppress feedback when engaged in conversation. Other VoIP companies are ahead of the game: telephone-like handsets can be purchased which connect to your computer in the same way as a headset, while others offer adaptors which plug into your broadband connection, and to which you simply connect a standard telephone. This eliminates the need for your computer to be switched on, allowing your VoIP line to behave just like a normal landline.

But does it? Fizz, dropouts and crackle are still commonplace when networks are congested. Some providers don't give you the opportunity to receive calls via VoIP, only make them, and many are unable to provide access to emergency services. Then there are hidden costs: many rates are advertised as being free of charge, but as a broadband customer you're already paying out as much as £30 a month to have the facility to use VoIP in the first place.

Rivals on the web

Skype

The best-known VOIP provider. www.skype.com
Type: Computer and headset.
What do I need? A computer running either Windows 2000/XP, Mac OS X, Linux or Pocket PC, along with the Skype program which is a free download.
How much to get started? Nothing, although if you want to call landlines (rather than other Skype users) you need to pre-pay.
Incoming calls? Yes. There's a bolt-on Sky service for £10 per month; you can choose a telephone number based in a range of countries or UK cities.
Rates? UK landline: 1.15p/min.
UK mobile: 13.9p/min.
US landline: 1.15p/min.
Good call: Neat software, and free calls between Skype users, of which there are an ever-increasing number.
Hang-ups: You're tied to your computer. There have been complaints about time-lag.

Vonage

A US-based company which expanded into the UK earlier this year. www.vonage.co.uk
Type: Adaptor and telephone, although once you've signed up and got your adaptor you can choose to bypass it.
What do I need? The Vonage adaptor, which costs £16.99. The software option requires Windows 98/ME/2000/XP, or Mac OS X.
How much to get started? £16.99 for the adaptor, plus £6.99 shipping.
Incoming calls? Yes. You can choose from a large range of UK-based STD codes.
Rates? Paying the flat rate of £9.99 per month gets you:
UK landline - free.
UK mobile - 15p/min peak, 10p/min evenings, 5p/min weekends.
US landline - 2p/min.
Good call: The start-up costs are low for an adaptor-based system.
Hang-ups: The flat-rate option might not suit light users.

Callserve

Founded in 1999, and one of the first providers to use the SIP standard for internet telephony. www.callserve.com
Type? Computer and headset.
What do I need? A PC running Windows 98/NT/ME/2000 or XP, along with a web browser and Callserve's Internet Telephone software, which can be downloaded for free.
How much to get started? Nothing, although your calls have to be prepaid.
Incoming calls? No.
UK landline - 3p/min. UK mobile - 15p/min.
US landline - 3p/min.
Good call: Free start-up and competitive worldwide rates.
Hang-ups: Only usable with a PC, and the rates within the UK are significantly greater than its competitors.

VoIPCheap

The software is still in beta (i.e. being tested for bugs) but the service is operational and very cheap. www.voipcheap.co.uk
Type? Computer and headset.
What do I need? A PC running Windows XP or 2000, and the free VoIPCheap software.
How much to get started? Nothing.
Incoming calls? No.
Rates?
UK landline - Free.
UK mobile - 9.75p/min.
US landline - 0.5p/min.
Good call: Astonishingly cheap across the board, including, for example, free calls to Australian landlines. And with no start-up costs or monthly fee, it's a mystery how they make any money.
Hang-ups: Computer-only operation. The beta software may not be trouble-free.

BT Communicator

This is BT's internet telephony "solution", rolled up with Yahoo!'s Messenger program. www.bt.com/communicator/
Type? Computer and headset.
What do I need? A PC running Windows 98/2000/Millenium/XP. If you choose to use Communicator's Clic2Call, you'll need a headset (£5), or there's the Clic2Connect option, where you use your computer to set up the call between your landline and the destination, which doesn't require any extra hardware.
How much to get started? Nothing, but to call to other landlines using the service you need to have a line with BT, even if your broadband connection isn't with them.
Incoming calls? Only from other users of BT Communicator.
Rates? UK landline and mobile: as your normal charges from BT; US landline: 0.5p/min (until 31 Dec). If you use Clic2Connect, there's a 1p connection charge for each call.
Good call: International rates are very good, particularly at the moment.
Hang-ups: You're tied to your computer to make the calls.

Gossiptel

A company which cut its teeth supplying voice networks to the military. www.gossiptel.com
Type? Computer and headset, or adaptor and telephone.
What do I need? If you prefer to cut the computer out of the loop, the adaptor for your telephone will cost £79.99 from Gossiptel, although the service works with any device based on the SIP standard. Otherwise, it's the free X-Lite software option, which runs on PC, Mac or Linux.
How much to get started? Nothing, apart from the adaptor if you want it.
Incoming calls? Yes. You can choose a UK number if you're on a monthly plan, or be assigned an 0870 number on pay-as-you-go.
Rates? UK landline: 2.5p/min peak; 1p/min evenings & weekends; UK mobile: 15p/min peak; 10p/min evenings; 6p/min weekends; US landline: 2.5p/min. A monthly plan will cost less: £9.99/month will get you 500 free minutes to landlines and mobiles in certain countries, and 1.5p/min thereafter.
Good call: The monthly plan offers exceptionally cheap international calls.
Hang-ups: Those great rates aren't available to UK mobiles.

Wanadoo

The largest ISP in Europe. Its broadband customers can upgrade to an internet telephony option called "Wireless & Talk". www.wanadoo.co.uk
Type: Adaptor and telephone.
What do I need? The Livebox modem, supplied free by Wanadoo. You'll need to have your broadband connection with Wanadoo; if you don't, the monthly charges range from £14.99 to £27.99.
How much to get started? Nothing, as long as you're already a Wanadoo customer.
Incoming calls? Yes. You're assigned an 0845 telephone number.
Rates? The flat rate of £4 per month gets you:
UK landline - 2.5p/min peak, free evenings and weekends.
UK mobile - 10p at all times.
US landline - 4p/min.
Good call: Cheap start-up costs and monthly rate; the cheap calls to UK mobiles are an advantage during the week.
Hang-ups: International calls are restricted to 20 countries.

Freetalk

Recently launched by DSG International (Dixons) as a direct competitor to BT. "We break the mould of traditional telephony," they say. www.freetalk.co.uk
Type? Adaptor and telephone.
What do I need? The adaptor, which you can buy from Dixons, Currys, The Link or PC World.
How much to get started? If you go for their option of paying annually, it's £79 up front with a free adaptor. A monthly rate is £6.99, with £20 on top for the adaptor.
Incoming calls? Yes. You can a choose a number from any area code in the UK.
Rates? Charges are the same for the annual or monthly option:
UK landline: free.
UK mobile: 15p/min peak, 10p/min evenings, 5p/min weekends.
US landline: 2p/min.
Good call: You're not tied to your computer - it's just like having another separate phone line. The worldwide calling rates are very competitive.
Hang-ups: It's a pricy start-up charge if you choose to pay annually.