Home

How to become an ISP

Modems (page 2)

There are two basic types of modems: Analogue and Digital.

Analogue modems are the type that people use in their personal computers. In countries where telephone line quality is poor or digital lines are not available, analogue modems are the best choice. For most ISPs, however, digital lines are the standard.

With analogue modems your subscribers can connect at a maximum speed of 33.6kbps. When data compression (built into the modems) is added to the figure, speeds of 35k to 45k are commonly achieved.

With digital remote access servers your subscribers can connect at a maximum speed of 53kbps, although the maximum download speed is typically no more than 45k. Another advantage of using digital modems is that you can provide 64kbps and 128kbps ISDN service.

The biggest advantage to digital modems is reliability, and the biggest drawback is cost. Analogue modems will end up costing one-half to one-quarter that of digital ones, and the lines often have one-half the monthly cost of digital. However, analogue modems have a tendency to stop answering calls from time to time. This can be corrected as it happens and there are methods to work around the problem, but it is an issue to consider nonetheless.

DSL and ISDN are pure digital formats, not modems at all. Digital transmission is much faster than analogue, even at the same speeds. These devices have the disadvantage, however, of only being able to transmit data over a short range (typically under 2 miles). As far as DSL is concerned, the cost of equipment can be prohibitively expensive for small ISPs. You'll need a few thousand subscribers before DSL is affordable. ISDN, on the other hand, goes hand-in-hand with the digital modems mentioned above. A digital remote access server can provide service for both 56k and ISDN customers.


© 1999-2008 Angelo Babudro   ·   Updated Thu, 04 Aug 2005 06:40:41 -0300   ·   Solo Deo gloria.
 Home