One of the problems with writing about new technology is that you never know whether something is going to have a lasting impact or simply turn out to be a fad. Some time ago, I was thinking about writing about Voice over IP (VoIP) or internet telephony, but the timing didn’t seem right.

At the time, VoIP was very much an enthusiasts’ toy, great for those who didn’t mind fiddling around to turn their computer into a telephone and were quite happy with sound quality that was little better than someone using a tin can and a long piece of string. Well, times have changed and while VoIP is still a minority pursuit, there’s little doubt that it’s here to stay. And when BT starts offering VoIP services, you have to start taking it seriously. In fact, BT is developing a new national phone network called 21CN (21st Century Network) based around internet protocol technology.

So why all the interest in VoIP? Well, because it offers new and interesting telephony features, is cheaper than traditional telephone services and it’s an inevitable consequence of the c-word - convergence. Most of the music we have at home is digital these days, which is why we can play it on our computers. DVDs and streaming video are also digital, and so is our telephony system. About 25 years ago, the UK telephone network went over to digital technology and as the internet is a digital network too, it makes sense to use that for voice telephony as well. Not that it’s been an easy ride.

Before broadband, internet telephony was a swine to use. A slow, dial-up connection meant lots of dropped calls, poor quality and poor reliability. But all that has changed. Broadband offers an always-on connection, you don’t pay for calls made from one PC to another and the faster data speeds available mean far superior quality and better reliability. Even so, it’s best to compare VoIP technology today with a mobile phone rather than a fixed line in terms of sound quality and reliability. In other words, it’s not perfect, but it’s perfectly adequate for making and receiving calls.

So what do you need to make internet calls? One way is to use your PC. You can download free internet telephony software like Skype, plug in a microphone and a pair of headphones (better still, use a microphone headset) and away you go, using an on-screen keypad and contacts list. You could even use a USB phone, which looks like a mobile phone but plugs into your PC. Prices start from around pound;30. There are also wireless wi-fi phones designed for VoIP calls, although the handsets are pricey at pound;150 each. The only problem with using this system is that the person at the other end of the line has to use the same VoIP software package as you - and you both have to sit at your computers to make and take calls. But Skype offers a service that allows you to make calls to ordinary phones and vice-versa for a fee. You can even pay for your own Skype number.

If you want to make internet calls away from a computer, you can buy a VoIP adapter which plugs into a broadband connection and an ordinary phone (prices from around pound;30). To use this facility, you’ll need to sign up to an SIP (session initiated protocol) provider that enables you to make telephone-to-telephone calls over the internet. SIP-to-SIP calls are free, but calls to conventional landline or mobile phones are charged, although at lower prices than on a conventional telephone network.

BT even offers a VoIP service to business and domestic users called BT BroadbandTalk, which works with standard telephones. You also get a new number for the service. BT currently has a special offer that runs until March 31, whereby you can pay pound;2 per month for six months (after which it is Pounds 4 per month) for free national calls at weekends and evenings for up to one hour (after that, it’s 3p per minute) or pound;7 a month (pound;10 after six months) for free calls of up to one hour at any time. Both VoIP packages also offer reduced charges for calls to mobile phones and international numbers.

With potential cost savings like these, it’s little wonder that more and more people and institutions are interested in internet telephony. But it’s not quite time to say goodbye to the good old telephone network yet. Remember, computers can crash, networks can go down, internet connections can fail and your home or school can suffer from power failure. For this reason, users of VoIP services need to have alternative arrangements in place for making emergency calls (in the same way that you must if you use cordless phones). Even so, there’s little doubt that over the coming years, more and more of us will be making phone calls over the internet.

www.skype.com

www.bt.combroadband