56K Modem General Info

The truth about 56K modems is that they have limitations. Users need to be aware that 56K modems are everything they've been promised to be and less. When using a 56K modem for web surfing, one can enjoy a substantial speed difference over a 33.6 Kbps modem, but on the other hand speeds for other tasks will vary.

The following connections do not support 56K acceleration:

  • upstream (user to ISP) transmissions
  • modem-to-modem connections
  • overseas connections
  • hotel/office connections through a PBX
  • connections made between incompatible 56K devices
  • connections made through older phone equipment

56K modems lack full-duplex capability. That means the modem can receive incoming data at 56-kbps, however can only send data out at 28.8-kbps. For users downloading web pages or browsing the World Wide Web, this is not a major concern as most of the traffic in these instances move towards the PC.

The limitations become evident when using two-way transactions such as video and data conferencing, or for FTP file uploads. As a result of restricted capability of sending data out at 28.8-kbps, 56K modems offer no benefit over the less expensive 28.8K and 33.6K modems.

In order to understand a 56K modem's limitations, you need to know what's behind analog modem technology. A modem modulates (translates) outgoing digital computer signals into audible analog tones, then sends those tones over the phone network. At the receiving end, a modem demodulates (recontructs) incoming analog tones into digital signals. During the conversion process, any interference from nearby electrical devices, flaws in the line or other connection problems can introduce errors into the signal. The receiving modem rejects any error-filled signal, forcing the data to be re-transmitted, therefore lowering the overall throughput. The faster the transmission speed, the more likely errors will occur.

Graphtronics uses digital lines. In this case, they do not need analog conversions and can, therefore operate at higher speeds. Because the phone company's lines are also generally digital in nature, the only real analog bottleneck will be at your "local loop", the segment between your modem and the telephone company's switching system. Unfortunately, because of this, Graphtronics has no control over your connection speeds... they are dependent on this local loop.

These pages might also be of help: Main modem info | Software modems | Connection help
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