How it works

What is it? VoIP (Voice over Internet Protocol) is a way to make phone calls using the internet as the transmission method, rather than a landline. You can make and receive calls from other VoIP users, mobile users, and people with ordinary landlines. The integration between any ordinary line and VoIP is complete and undetectable to callers. How does it work? Just like a modem converts digital signals from the PC into analogue (voice) traffic for transmission over a phone line, a VoIP-enabled phone or VoIP adaptor converts your voice into digital packets (using the special SIP protocol) for transmission over the internet. If you make a call to another VoIP phone, the opposite process occurs at the other end, and your voice emerges intact from the ether. If you make a call to a mobile or landline, your VoIP providers gateway decodes the call and sends it on as an ordinary voice call to the telephone exchange (PSTN). Calling another VoIP line See the diagram: user A dials the number for user B. The VoIP adaptor logs onto the routing server, which looks up the destination and sets up the call. Thereafter, the voice traffic passes directly over the internet between A and B. Calling a non-VoIP (standard: landline or mobile) line See the diagram: When A calls C, who has a conventional landline or mobile, the VoIP adaptor logs on as before. The routing server looks up the destination and finds it is a PSTN (standard) number. The call is routed via the providers PSTN gateway into the PSTN network as a normal call. Thereafter, traffic passes directly via the gateway. Why use it and who benefits? Small to medium-sized businesses with several employees, especially those with distributed offices and teleworkers, are likely to get the maximum benefit from VoIP. It cuts your business telephony cost; all calls to other VoIP phone users are free and other calls are usually competitively priced. You can configure your system to give whatever impression you want to customers. For example, if you have associates or employees in other areas of the UK or even abroad, you can give them all extensions on the same number, or their own numbers with the same area code as your head office. No-one need know whether you have city centre offices, or a virtual office! What will you need? 1. A VoIP enabled telephone: This can be an all-in-one handset, or a normal handset plugged into an adaptor, or a softphone: a computer program that uses a microphone and headphones attached to your computer to emulate a real handset. A good solution is an adaptor, which allows you to connect one or two handsets, and has the advantage that you can connect other analogue devices like fax machines. It also has a number of useful inbuilt functions, including call waiting, caller ID, and call back if busy. 2. An internet connection: A leased line or ADSL/cable broadband is ideal; dial-up (ISDN or ordinary telephone line) or a satellite internet connection will likely cause a reduction in sound quality. A standard 256Kb ADSL connection can accommodate 2-3 simultaneous calls; if you expect to need more frequently, you may wish to upgrade to a higher-bandwidth package. 3. An account with a VoIP service provider: This gives you a VoIP external number which is what other people dial to call you. What will it cost? Costs vary from between VoIP service providers. In general there will be a one off set up charge and monthly rental per number (for which you will usually receive one incoming and one outgoing line and a varying number of internal extensions.) VoIP to VoIP call's are free and calls to landlines and mobiles can vary across providers but are usually lower than landline service providers charges. Some VoIP providers offer monthly all inclusive packages combining monthly rental charges and unlimited calls.