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VoIP is the abbreviation for Voice over Internet Protocol and is the generic name used for making and receiving phone calls over IP networks.
[For more information on VoIP the "VoIP For Dummies" reference book is available from Amazon by clicking on the image to the left.]
An example of an IP network would be the Local Area Network (ie LAN) that connects together the computers and other devices in your office or home. Another example of an IP network would be a Wide Area Network (ie WAN) such as the public internet.
The main function of a VoIP device is to convert analogue and digital speech and dialling signals into the type of digital signal that can be transmitted over IP networks.
[NB The digital signals used by ISDN phones and phone systems are different from the digital signals used in IP networks in that the former is based on circuit switching and the latter is based on packet switching.]
Examples of VoIP devices are:
To find our more about these VoIP devices click the appropriate link in the above list.
It is important to note that VoIP devices are the same as traditional phones in that they require a host phone system to provide dial-tone. This could be a VoIP PBX phone system that would be connected to an office LAN, or it could be a public VoIP phone system that would be provided over a public internet WAN connection by a service provider such as Skype.
VoIP PBXs would also need to be connected (via the internet) to a public VoIP phone system service provider to enable their connected VoIP devices to make external calls. An example of a VoIP PBX would be the Aastra 400 which is discussed elsewhere on the Premitel website.
Before deploying VoIP it is important to understand the limitations of VoIP in terms of call quality. This is a significant issue for VoIP calls made over the public internet, less so for internal calls made over a VoIP PBX connected to a private LAN.
Anyone who has used Skype, or a similar VoIP service, will be aware that VoIP call quality can be variable. Sometimes quality is near perfect and at other times the call can be almost unintelligible. The reason for this is that the public internet is not designed to transmit real-time data such as that required for phone calls.
Businesses that are considering using VoIP for their external calls (rather than traditional analogue and ISDN lines) should be aware that, to ensure satisfactory call quality, they will need leased-line internet connections that are not subject to the sort of congestion that would have an adverse effect on call quality. They would also need a VoIP service provider that can process and route their VoIP calls in such a way that they have priority over other internet traffic.
Leased-line internet connections would typically cost several hundred pounds per month. This may make the switch to VoIP uneconomic for business that require fewer than 10 x VoIP lines.
If a leased line is not used and a VoIP device (or VoIP PBX) is connected to a standard £15 – £30 per month broadband internet connection then VoIP calls are likely to be subject to congestion and the various traffic management techniques used by internet service providers to ensure most efficient use of their internet capacity. The result would be variable quality for VoIP calls.
It is therefore our recommendation that, unless a customer has a dedicated broadband internet connection with the ability to prioritise VoIP calls, VoIP should not be used for primary phone lines where good quality reliable sound is essential. If this is not the case then VoIP should be used only for secondary lines. For example, to provide overflow capacity at busy times, or to provide a low cost (or free) hot-line to relatives overseas.
VoIP can also be used effectively for situations where the cost of installing regular phone lines would be prohibitive. For example, short term events or film/TV production offices on location.
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