Disadvantages of 56K

• Introduction

• Only one A/D conversion allowed

• 40 to 50K more likely

• 56K for downloads only

• 53K limit in the U.S.

• Requires digital lines at the ISP

• Won't work with some PBXes

Requires digital lines at the ISP

If you were one of the first people to buy a 28800 modem, you may have discovered that most of the places that you called still used 14400 modems, so you could only connect at 14400. It's always been this way with modems: they can only connect at the highest speed supported by both modems.

56K throws a new twist into the story. Yes, both you and your Internet service provider (ISP) must have 56K modems. Otherwise, you'll only connect at a maximum of 28.8K or 33.6K. There's more to it than that, though.

The whole concept of 56K technology depends on the ISP having digital phone lines connecting their modems to the phone company. The digital lines are much clearer than analog phone lines, so higher connection speeds are possible. And the real beauty of 56K is that the ISP has to have special phone lines, but you don't. 56K modems will work with the regular analog phone lines you have now.

So the ISP needs digital phone lines. Is that a problem? Maybe. Many ISPs already have digital PRI lines to support customers using ISDN. Even more use a digital T1 line to bring in analog phone calls from their customers' modems. Those ISPs are well on their way to offering 56K service.

The problem will mostly be with smaller ISPs who can't afford the investment needed to rebuild their infrastructure. The ISP market has become more competitive, with rates dropping and big fish eating little fish. The arrival of 56K will provide further competitive pressure, and may accelerate the consolidation of the ISP market.

How do you know if your ISP has digital lines and digital equipment? You can probably call your ISP and get the answer, but if the service offers ISDN, that's a good sign. They definitely have digital lines and digital equipment if they use Ascend MAX terminal servers.