Joseph Thomas wrote the following to All, and I quote (in part):
 JT>   HEy Modem GURUS, what is this X2 and OR 56FLEX ?
[Excerpted from the COMM echo primer]
56Kbps Modems (X2 - K56Flex) - Rockwell, USR, Lucent Technologies, and    
Motorola have recently announced plans to market chipsets/modems that     
operate in a server/client format at up to 56Kbps over standard telephone 
lines. The 56kbps speed is asymmetric, can only be achieved if the server 
has a direct digital connection to the network, and there is only one     
analog segment in the phone network along the path from the server to the 
client.                                                                   
                                                                          
The technology is based on eliminating restrictions imposed by the        
conversion of analog signals to digital form in the downstream data path  
(server -> client). Data flow in the server to client direction does not  
occur in the form of a modulated carrier, it is instead sent as binary    
numbers representative of 256 possible voltage levels. The reason for the 
asymmetrical send/receive rates is because in the direction from the      
client to the server it is not possible to use a digital coding scheme    
and make it work as well as v.34 does, thus V.34 is used instead.  It     
isn't possible because the telco's line card has a codec that is a much   
better digital level changer for the transmit direction than it is for    
the receive direction. The codec used in the customer's modem is, in that 
respect, somewhat more sophisticated and was designed to work as a fairly 
good level changer in the receive direction (which the telco's codec was  
not designed to do).                                                      
                                                                           
    Note: Achievable bit rates with X2 are limited to less than 56kbps     
    by FCC regulations, and X2 is also incompatible with the K56LFEX       
    Rockwell/Lucent/Motorola implementation.                               
                                                                           
 JT> are these two going to be some kind of standard soon ??
Neither will become "THE" standard, but the International Telecommunications 
Union is currently in the process of developing a standard. A likely time 
frame for adoption is mid-late 1998.
[Note to Dave/Rick: feel free to use what you desire from the primer]
Regards....
Craig
aka: cford@ix.netcom.com
   : craig.ford@2001.conchbbs.com
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