Internet Access Guide : Introduction

Picture: Internet Access
A typical Internet user surfs the Web. Between her and the ISP PoP is the access network.

Internet access service is offered by an Internet Service Provider (ISP). The ISP has the necessary equipment for connecting its subscribers to the Internet such as modem pool, access server, RADIUS server, and routers.
National ISPs usually distribute their equipment to many locations in order to be closer to their subscribers. They have many PoPs (Points of Presence) that let their subscribers dial a local number instead of a long distance number or connect over a shorter line. An ISP's PoP is the interface between the ISP and its subscribers.
Internet access is the way a subscriber connects her modem to her ISP's PoP. The connection may go through other operator's network, usually telephone network (if using dial-up or DSL modem) or CATV network (if using cable modem).

The following are common Internet access scenarios :
- Companies pay to telecom operators for leased line (E1/T1), satellite link, or radio link to connect their networks to their ISPs.
- Residential users mostly use dial-up modem to dial their ISPs. Dial-up modem (i.e. V.34, V.90, V.92) is still in widespread use all over the world.
- Residential users who need broadband connection mostly use DSL or cable modem.
- Public places such as university campuses, hotels, airports, and cafs offer Internet access through Wi-Fi hotspots. The Wi-Fi hotspots are connected to the Internet using leased line, DSL, or cable modem.
- Mobile workers access the Internet using their mobile phones as modems that connect their laptops to the Internet through GPRS network or other types of mobile data networks such as EDGE and EVDO. In most cases, their mobile phone operators also act as their ISPs.
- Mobile phone users surf the Web using small screen browsers (micro browsers) that support WAP (wireless application protocol) over GPRS or other types of mobile data networks.
- Traveling executives connect to the Internet during inter-continental flights through airplanes' local networks that have broadband link to earth stations.