High-speed modems are designed to process digital information much more quickly than a traditional phone line with an analog connection. High-speed modems are often designated as 56k modems, meaning they can upload 56,000 bits per second. A high-speed modem should significantly increase the speed of your Internet access.

On the Other: Other Factors Influence Speed

Unfortunately, just putting in a high-speed modem will not guarantee faster web page uploads. Other factors can all but negate the speed that should be gained by installing a high-speed modem. These include inadequate phone line bandwidth, a slow computer processor, incorrect computer settings, website server speed, system infection from malware, and your Internet service provider's network capacity and traffic levels.

Bottom Line

A high-speed modem is a step toward having faster Internet downloads. However, it is a only a link in the chain. The computer you work on must to be able to handle the speed the modem provides, and inadequate bandwidth to carry signals can create bottlenecks. If capacity and functionality are adequate across these areas, then a high-speed modem will be able to do its job.

Source:

Modem Help: 56K

Qwest.com: Internet Help