What is Bandwidth?
Bandwidth is interchangeably used with connection speed, although technically they are not exactly the same. Bandwidth is in fact a range of frequencies through which data is transmitted. The same principles apply for radio, TV and data transmission. A large bandwidth ‘range’ means that more data are transmitted at one point in time, and thus at greater speed. Technically, bandwidth is not connection speed, although they are used interchangeably by most Internet users. I will do so as well, to put you at ease.
Measuring Bandwidth
Bandwidth is measured in Hertz (Hz), or MegaHertz (MHz) because Hertz are counted in millions. One MHz is one million Hz. Connection speed (technically called the bit rate) is measured in Kilo bits per second (kbps). It is simply a measure of how many bits are transmitted in one second. I am going to use kbps or mbps to refer to transmission speed from now on, because that’s what every service provider talks about when referring to the speed they offer. One mbps is one thousand kbps.
You can have an idea of how good or band your connection speed is and whether it is suitable for VoIP by performing online connection tests. Read more on connection tests here.
Bandwidth Cost
For most people using the Internet as a communication medium, bandwidth happens to be the most expensive requirement, because it is recurring. For voice communication, the bandwidth requirements are more important, since voice is a type of data which is bulkier than conventional text. This implies that the greater the connection speed, the better the voice quality you can get. Today, broadband connection is common talk and getting cheaper and cheaper.
Broadband is unlimited connection (24 hours a day) at a speed much higher than that of dial-up’s 56 kbps. Most providers give at least 512 kbps today, which is largely sufficient for VoIP communication. This is the case for developed countries and regions. For other places, some users are still restricted to low connection speed at high prices.
Common Bandwidths
Let’s have a look at some typical bandwidth associated with popular communication devices and technologies.
| Technology | Speed | Use in VoIP |
| Dial-Up (modem) | Up to 56 kbps | Not suitable |
| ISDN | Up to 128 kbps | Suitable, for fixed and dedicated service |
| ADSL | Up to several Mbps | One of the best WAN technologies, but provides no mobility |
| Wireless technologies (e.g. WiFi, WiMax, GPRS, CDMA) | Up to several Mbps | Some technologies are suitable, while some are limited by distance and signal quality. They are the mobile alternatives to ADSL. |
| LAN (e.g Ethernet) | Up to thousands of Mbps (Gbps) | The best, but limited to the length of wires which can be short in most cases. |
| Cable | 1 to 6 Mbps | High speed but limits mobility. Is suitable is you don't have to move. |
