You need 4 things to enable you to do this; a subscription to broadband ISP, a VoIP provider and a normal phone, an analogue telephone adapter (although you can just use a computer software 'phone' which is generally free to download and use).
Choosing the VoIP provider is likely to be the hardest of the choices you need to make. You need to decide which of the many plans from the many providers suits your calling pattern best. Most offer extremely competitive national and international calls, some even with unlimited duration. You do still need to keep you existing phone line though. You need it to get your broadband, you'll also need a 'fall-back' because in the case of a power cut your VoIP won't work.
Be sure to choose a VoIP provider that will give you a normal area based VoIP phone number - an 01 or 02 number. Some providers cut corners and only provide an 0870 number which means that either people will be charged a lot to call you or you'll have to keep using your old POTS phone for calls in, it's a messy solution whichever you end up doing.
Once installed, VoIP works just like a normal phone: pick up the phone and you will hear a dial tone; dial a phone number, wait for the person to answer and start talking, just as you do now. In most cases the person on the other line won’t even know that you're using VoIP.
Some of the benefits of using broadband phone service can include: unlimited calling to the some destinations (depending on the provider), free features like call waiting, caller id, call forwarding, follow me, find me, three-way calling, online billing, voicemail, voicemail to email or text notification, and the ability to choose your area code. This means for example, that you can live in Stroud and have a London phone number making it cheaper for people in London to call you.
VoIP is not restricted to one phone line though, you can buy ATAs which let you connect 2 or 4 phones giving you the ability to add extra lines whenever you want. For a small charge, some providers allow you to have a 'virtual number' which is a number in a different area code, that when dialled rings directly to your main number. Virtual numbers eliminate long-distance phone charges for anyone calling within that numbers' area code.
Another advantage of a VoIP service is that in certain circumstances, you can make totally free calls. If both you and the person that you are calling are using the same VoIP provider or one of any number of providers that your provider is linked with, there will be no charge for the call. You will however need to verify that both ends of the call are subject to the free call so if this is your aim, it's best to double check this "before" signing up.
Skype is a type of VoIP that has received a lot of press in the recent past. However it differs from 'traditional' VoIP in that it is a peer to peer VoIP solution which uses its own proprietary protocol. The disadvantage is that these products will not inter-operate with anything else. This may not seem such a bad thing to users of Skype, with its millions of members, but it might be inconvenient in the future. The benefit of free Voip-to-Voip calls will only be realised if all your friends and contacts are also using the same service. This may not be too limiting if you choose Skype, due to its widespread popularity. But before choosing it, consider the disadvantages of being locked in to a proprietary service which through its position of strength has no need to try to compete on services or pricing. Skype is probably best kept as an additional service to contact those family and friends who also make use of the service rather than being thought of as taking over instead of your normal phone.
Some UK VoIP Providers
Vonage
Voiptalk
voipfone
Sipgate
- Please note that these are simply provided for quick reference, their inclusion here isn't meant to be a recommendation.

