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  PC-Net's PC News - July, 1998
Don Watkins

Modem Math 101: 56 Does Not Equal 56
(And the FCC Says It Can Only Equal 53)

By Don Watkins



July 1998--You just bought a shiny new 56K modem and have connected it to your system. You fire it up and see a maximum connect rate of 33.6. You check the box and manual and verify that it says 56K, so you try again. But 33.6 returns as if etched in stone. You scratch your head, think you may have a bad modem, and return it for another. Same results. Scratching your head you figure you're cursed.

Sound farfetched? Not based on the many messages from the newsgroups here. The modem world is in a state of transition and probably will be until at least September and possibly longer.

When 56K modems were introduced, there were two different versions, one developed by USR (now called 3Com) and another by Rockwell and Lucent Technology. USR/3Com's version is called "X2" and the Rockwell/Lucent method is called 56Kflex. And as things go in the computer world, the two are not compatible. This means if you purchased an X2 modem and try to connect to an Internet Service Provider that only supports 56Kflex, the maximum connect speed you will get is 33.6.

The two different companies have worked out the differences in their products. The new method is called v.90 and it is expected that it will be ratified later this year. Once that happens, ISPs and modem manufacturers will finally be able to produce products that will work everywhere.

Some modem vendors have already started releasing v.90 support for their modems. However many ISPs have not yet installed v.90 code on their equipment, which means that to achieve a 56K connection today, you need a modem that supports the version of 56K the ISP is using.

There is an additional "gotcha" with the 56Kflex modems. The first modems that were produced were capable of being updated to v.90 by a software upgrade. However, it appears that the modems are only able to store one type of 56K support, either 56Kflex or v.90. If the v.90 code is installed, a user could no longer achieve a 56Kflex connection and if the ISP didn't have v.90 support the connection dropped down to 33.6.

We suggest you wait till your ISP has upgraded to v.90 before upgrading your 56Kflex modem. X2 modems do not have this problem. They have the ability to store both X2 and v.90 support in the modem and use whichever version the ISP supports.

Next month, we will continue the 56K discussion and examine why the 56K connection is "one-way" only.


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