About 56K Line Access
Appendix G
About 56K Line Access
The Netopia R2020 is capable of 56Kbps per line connections. This means that if you use both onboard modems, you can achieve inbound data transfer rates of up to 112Kbps. Using a third modem bumps the theoretical speed limit to 168Kbps.
This section describes some practical limitations on the previous statements.
A current FCC limitation will only permit a maximum speed of 52Kbps over analog phone lines using combined analog/digital technology. Also, the data transfer rates are for inbound data only. Outbound data is limited to the current transfer rates for analog phone lines alone which is 33.6Kbps. So, using both onboard modems under optimal conditions, will yield an inbound data transfer rate of 104Kbps and an outbound rate of 67.2Kbps. This means that your incoming email, file transfers and downloads, web browsing, and so on, occur at 104Kbps, while your outgoing information, such as outbound email, travels at 67.2Kbps. With a third modem, the rates become 156Kbps inbound and 100.8Kbps outbound. Also, to achieve the maximum inbound rates, the
Outbound data
33.6K
67.2K
33.6K
Inbound data
56K
112K
56K
Above a certain threshold (called Shannon's Limit) the
Today's telephone network is increasingly digital. In particular, the portion of the phone connection between the phone company and the Internet Service Provider (ISP) is often digital. Digital lines still have noise, and are still subject to Shannon's limit, but they have less noise and a higher ceiling.
Several companies have created techniques that take advantage of the digital portion of the phone network to achieve higher speeds than were possible with a purely analog pathway.
