1. Introduction

If we go back in history, the Internet has evolved from basic dial-up access using traditional telephone lines to the current state of high-speed broadband access. Several years back, people were accessing the Internet using a dialup modem at a speed of about 9.6 kilo bits per second (kbps). Please note that KBPS is normally used to denote Kilo Bytes per second, which is usually 10 times that of kbps. That is, a speed of a bout 0.96KBPS. At this rate, a video clip of size of 1MB download is going to take several minutes! The article begins with traditional dialup access and moves on to most recent technologies like VDSL, WiMAX, and 4G.

a. Dial up Internet Access

Dialup Internet access is a service provided by ISPs (Internet Service Providers) that allows connectivity to the Internet through a standard telephone line using copper twisted pair (TP). The following diagram shows the typical connection to the customer premises equipment (modem) from the local exchange office.

Here one end of the telephone line is connected to the modem, which can be an external or internal to your computer, and the other end is inserted into the phone jack. You need to configure the computer for dialup access and need to load the system with appropriate driver for connecting to the modem. The modems are usually belongs to the customer, and manufactured to comply with international standards for modem protocols. At the other end, the ISP will also have matching modem rack that contains several such modems, one for each customer. Some times, several modems are clubbed in to one physical hardware rack, and known as modem rack.

Dial up Internet service is provided through several ISPs and usually requires the permission from the government to operate. The protocol that is used to connect a modem to its peer at the other end (located at the local exchange) is called PPP (Point to Point Protocol). There are different types of modems, and most of them are inexpensive to purchase. You can have an internal modem installed in a free slot of your computer, or you can have an external modem that's hooked up to the computer through cables. A telephone line is linked to the modem.

Any computer Operating System like Microsoft Windows has Network Connection utility, which allows you to connect to the Internet. In the Network Connection utility you have to set up ISP profile so that the modem knows what phone number to dial, and other connection parameters so that you can connect to the Internet. When the modem dials the phone number your ISP gives you, a connection is made, and then information is transferred between the modem and the remote server. A remote authentication server is the computer and related software that is established to handle users who want to access a network remotely. The username and password are required to access gateway to the Internet. The gateway to the Internet is a network that allows entry into the Internet.

The modems that are utilized in todays senario have maximum speeds upto 56 kbits/s. With some multiplexing, it may be possible to increase the speeds a little further, but not enough to meet the existing demands. For example, contents such as 'streaming media' may not be viable using traditional dialup access. Further, services like video conferencing and online gaming, does not work properly with a dial up internet connection.

b.Limitations of Dial Up Internet Access

• Slow access
• Limited bandwidth
• Cannot use phone and web at same time