Dial-up connections
Dial-up connections are the most common type of internet connection available from ISPs, they are also the slowest and (usually) the most inexpensive.
A dial-up connection allows you to connect to the internet via a local server using a standard 56k modem, your PC literally dials (hence the name) a phone number (provided by your ISP) and connects to the server and therefore the internet.
Once connected you can utilise all aspects of the internet, the drawback with a dial-up connection is the speed, a standard 56k modem can theoretically transfer 56 Kilobits of data a second, this means that you can (again theoretically) transfer up to 7 Kilobytes a second (although to get a full 7k is near impossible due to the compression overhead).
When you consider the average web page including images is around 50 Kilobytes, this means it would take around 7 seconds for the web page to completely load in your browser.
On top of this most (though not all) internet service providers charge by the minute for your connection, so the longer it takes to load the pages you visit, the more you pay for your connection. The cost is usually the same as you would pay for a local phone call so as long as they are used sensibly they can be a very cost effective internet connection.
Dial-up connection Pros
Dial-up connections can be very economic and are widely available, the cost is usually the same as a local phone call or priced as a monthly plan. As these connections use a standard modem the hardware costs are minimal.
Dial-up connection Cons
Dial-up connections are very slow compared to other connection types. When connected to the internet the same phone line cannot be used for phone calls so if anyone phones you when you are connected they will get the busy signal.
Dial-up connections transfer data over an analogue line so before the data is sent it has to be converted from digital to analogue, likewise when data is received it has to be converted from analogue to digital (this is what the modem does), this adds a performance overhead which affects the speed of the connection.
ADSL (Asymmetric Digital Subscribers Line) connections are becoming more and more widely available and can provide an excellent internet connection.
The connections work by splitting your phone line into two separate channels, one for data (internet) and one for voice (phone calls) which means you can talk on the phone and be connected to the internet at the same time.
You will often see ADSL connection services advertised as having different speed specifications, below are some common configurations:
- 256Kbps/128Kbps
- 512Kbps/128Kbps
- 1Mbps/256Kbps
Notice there are two values to each configuration, the first figure states the download speed and the second figure is the maximum upload speed.
As an example let's take the second configuration 512Kbps/128Kbps, this means that you can potentially download data at a speed of 512Kbps and upload data at 128Kbps.
The most important figure is the download speed, this depicts how long it will take to view a web page, download a music file or an email attachment.
As an example of how the different download speeds can affect your connection, below are some figures to give you an idea of the differences:
Average Web Page (50 Kilobytes including images)
- 256kbps download speed - roughly 1.56 seconds to view page
- 512kbps download speed - roughly 0.78 seconds to view page
Average MP3 file (music file) (4 Megabytes)
- 256kbps download speed - roughly 2 minutes and 8 seconds to download.
- 512kbps download speed - roughly 1 minute and 4 seconds to download.
The figures above are theoretical as there are many other factors which determine the real download speed (such as the speed of the server/host you are downloading from).
As you can see ADSL offers incredible performance compared to standard dial-up connections and is becoming the first choice for most internet subscribers.
Most ISPs that offer ADSL packages charge a flat monthly fee which normally includes a certain amount of bandwidth each month
ADSL connection Pros
Apart from the obvious speed advantages that ADSL connections offer, ADSL technology eliminates the need for a second phone line by allowing voice and data transfer at the same time (you can use the phone as normal while connected to the internet).
Because ADSL transfers data digitally it eliminates the usual performance overhead associated with standard dial-up connections, in other words ADSL doesn't need to convert the data from digital to analogue and back again.
ADSL connections are Always on, which makes the usual long wait to connect a thing of the past.
ADSL connection Cons
ADSL connections are not available to everyone, you should always ensure that you have ADSL coverage in your area (an ISP will check for you). The hardware costs can be quite significant as you will need a special ADSL modem and ADSL filters to use the service, most ISPs allow you to hire these items which can reduce the initial cost.
Because ADSL connections are Always on you will need a firewall to protect your PC.
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