Promoted practically to the point of exaggeration by U.S. Robotics, Lucent Technologies, and Rockwell Semiconductor Systems, these new techniques for 56-Kbps transmission over phone lines can be considered the modem's last stand. But their allure is obvious. The drawbacks cannot be ignored. You need to access a service provider that has the hardware support for whatever 56-Kbps scheme you are using. The host you're calling also must have a digital connection to the Internet or corporate network.
Uploading speeds are slower.
Most important for the near term, all 56-Kbps solutions today are proprietary, and standards are not expected before next year. But the core network infrastructure is largely in place for 56-Kbps service, which looks to diminish the appeal of ISDN for data services over the next ten years. Satellite data delivery has its share of drawbacks, including relatively costly start-up fees, but like ISDN, it's here today. Unlike ISDN, it's available anywhere in the U.S. that has a clear line of sight to the service's satellite. It's a great technology, but depending on the physical layout of your home or building, satellite data service may not be a viable option.