56k Modem Standard and Trend

V.90 Standard

Until recently, 56k modems used to come in two incompatible versions. One version used the X2 protocol developed and used by USRobotics. The other version used the K56flex protocol developed by Rockwell Semiconductor Systems and Lucent Technologies. K56flex was used by the majority of other manufacturers. The names "X2" and "K56flex" are tradenames for different ways of getting modems to connect at speeds higher than 33.6 kbps. To get a "56k" connection one must be dialing an Internet Service Provider (ISP) whose equipment supports the 56k protocol used by a particular modem manufacturer. That is, an X2 modem would connect at speeds above 33.6 only if it is dialing an X2 ISP. Likewise a K56flex modem would connect at speeds higher that 33.6 only if it dialing a K56flex ISP.

The 56K modem war is over, with an important ITU agreement reached February 6th, 1998 in Geneva, Switzerland. V.90 is the common protocol for 56k modem and it is neither fully K56Flex or X2 but rather a hybrid of both.

A 56K interoperability standard is important because it enables 56K connectivity regardless of the modem manufacturer at the other end of the telephone line. Prior to the V.90 modem standard, modems from different vendors (K56flex and X2) only connected to each other at V.34 (28.8kbps) speeds. Now, with a simple V.90 flash upgrade, 56K connection speeds are possible, regardless of manufacturer. As soon as ISP's deploy V.90 code at their POPs, users that get flash upgrades to bring their X2 or K56flex modems to run V.90 won't care what kind of central site equipment is at their ISP, both will work.

The Trend of Modem

The real competition is with high-speed technologies like ISDN, cable modems, and the xDSLs (ADL, SDSL, etc.) All of these technologies are faster than 56K, and some are much faster. 56K has real-world advantages that ensure that it will be more popular than all of them for the near future.

ISDN still isn't widely available. To be able to get a connection to ISDN, you need to get within 6 km to a nearest ISDN switch. ADSL, with less availability, has a limit of 6 km from the phone company central office. Even worse, ADSL usually requires co-location of equipment in the local telephone company's offices, which may lead to virtual monopolies on ADSL from the phone company's own Internet service division. Cable Internet access is limited to less than 1% of the U.S. market right now, simply because few cable companies have the infrastructure to offer it. However, that number could grow dramatically in the next two years. However, just like old 28.8k modem, 56k is just a transition phase towards faster and more efficient data transmission technology. The only question is how long it will last.