US Robotics Courier V.Everything x2 Addendum User manual

Courier™V.Everything™
Command Reference Addendum
Macintosh Modems
Congratulations! You have just purchased a U.S. Robotics Courier
V.Everything that is x2-capable. x2 is a groundbreaking new technology
that allows your modem to use normal analog phone lines to connect at
speeds up to 56 kbps.
Information about x2
For more information about x2, visit the U.S. Robotics x2 Web Site
at http://www.usr.com/x2

2
The material contained in this document is for information purposes only and is
subject to change without notice. U.S. Robotics makes no representations or
warranties with respect to the contents hereof and specifically disclaims any
implied warranties of merchantability or fitness for any particular purpose.
No part of this document may be reproduced, transmitted, transcribed, or stored
in a retrieval system in any form or by any means, mechanical, magnetic,
electronic, optical, chemical or otherwise, without the written permission of
U.S. Robotics.
U.S. Robotics and the U.S. Robotics logo are registered trademarks of U.S.
Robotics Access Corp. Any trademarks, tradenames, service marks or service
names owned or registered by any other company and used in this manual are
the property of their respective companies.
U.S. Robotics assumes no responsibility for errors or omissions in this manual.
Nor does U.S. Robotics make any commitment to update the information
contained herein.
1996-1997 U.S. Robotics
8100 N. McCormick Blvd.
Skokie, IL 60076-2999 USA

Contents
Contacting U.S. Robotics 1
Enhanced x2 Features 1
How to Tell if x2 is Enabled in Your Modem 2
How x2 Works 3
The Shift from Analog to Digital Circuits 3
Client and Server Modems 3
Client Modems 4
Server Modems 4
Making x2 Work 4
A Digital Connection At One End 4
Only One Digital-to-Analog Conversion 4
Controlling x2 5
Controlling Link Speeds with &N and &U 6
Controlling Link Speeds 6
Limiting the Highest Possible Connect Speed 6
Limiting the Lowest Possible Connect Speed 6
Limiting a Range of Possible Connect Speeds 7
&N and &U Command Values 8
Configuring the High Speed (HS) LED 9
Troubleshooting x2 Client Connections 10
New x2 Result Codes 11

Courier V.Everything x2 Addendum1
Contacting U.S. Robotics
We’ve made every effort to provide you with useful, accurate information. If
you have any comments or questions, please let us know.
To do this
Contact
Contact U.S. Robotics Technical Support
800.550.7800
Visit the x2 web site
http://www.usr.com/x2
Enhanced x2 Features
Your Courier I-modem with x2 has new result codes and the following new
features. Refer to later sections of this Addendum for more information.
To do this
Use this command
Detemine if x2 is enabled in your modem
ATI7
Disable or enable x2
ATS58
Limit the upper speed limit of an x2 connection
AT&N
Limit the lower speed limit of an x2 connection
AT&U
Configure the High Speed (HS) LED
ATS69
Note: New x2 features should be transparent to most users. If you are an
advanced user, see ”Controlling x2” and “Controlling Link Speeds with &N
and &U” for detailed information regarding these new features.

2
How to Tell if x2 is Enabled in Your Modem
If you aren’t sure whether x2 is enabled in your Courier modem, use theATI7
command to display product configuration information. If x2 is enabled on
your Courier modem, the following information displays:
USRobotics Courier I-modem Configuration Profile...
Copyright, 19xx-96, U.S. Robotics. All rights reserved.
Product type US/Canada External
Options HST,V32bis,Terbo,VFC,V34+,x2
Fax Options Class 1,Class 2.0
Clock Freq 20.16Mhz
Eprom 256k
Ram 32k
Supervisor date 02/01/97
DSP date 02/01/97
Supervisor rev 7.0.0
DSP rev 2.0.0
Serial Number {serial number}
OK
Note: Dates, serial numbers, and revision numbers may vary. The most
important line is the “Options” line, which lists support for x2.

Courier V.Everything x2 Addendum3
How x2 Works
U.S. Robotics' x2 technology enables analog modems to receive data at up to 56
kbps over the standard analog, public switched telephone network (PSTN). x2
overcomes the limitations imposed on standard, analog modems by exploiting
the digital connections that most Internet and online service providers have at
their end to connect to the PSTN.
The Shift from Analog to Digital Circuits
When the first telephone networks were established, they were completely
analog. Over time, telephone companies began replacing portions of their
analog networks with digital circuits, which provided a higher telephone signal
quality at a more economical price.
Today, the PSTN is almost entirely digital. Typically, the only portion of the
telephone network that remains analog is the line that connects your home to
the telephone company's central office (CO). The rest of the telephone network
is digital.
Client and Server Modems
x2 will not require changes to your wiring and equipment that's already in
place. All that's required to use x2 is a software upgrade.

4
Client Modems
x2 client modems can receive data at speeds up to 56 kbps and send data at
V.34 speeds. The following products are examples of U.S. Robotics Client
Modems:
• Courier™ V.Everything™ with x2
• Sportster® with x2
• Analog Modem Pools or NETServer with x2
Server Modems
The digital x2 modems that client x2 modems connect to are called server x2
modems. Server modems can send data to client x2 modems at speeds up to 56
kbps. A server must have a “digital” interface to the PSTN. This digital
interface can be in the form of a “trunk-side” T1, Primary Rate Interface (PRI) ,
or Basic Rate Interface (BRI). The following products are examples of client x2
modems:
• Courier I-modem with x2 (in Server Mode)
• Quad Modem 5.0/5.1 (in Server Mode)
• MP I-modem or NETServer I-modem with x2
Making x2 Work
To use x2, the client x2 modem must connect to a server x2 modem. If clients
attempt to connect to ISPs that do not use x2, the client modem will negotiate
the next available modulation. For example, an x2 client modem calling into an
ISP that only supports V.34, the modem will only negotiate the highest v.34
connection rate. The maximum V.34 connection speed is 33.6 kbps.
When a client x2 modem connects to a server x2 modem, the path through the
telephone network between the modems is subject to the following conditions
for an x2 connection to be made.
A Digital Connection At One End
ISPs or online services must have a digital connection to the PSTN. Most major
online services have digital connections to the PSTN.
Only One Digital-to-Analog Conversion
There can be only one digital-to-analog conversion in the telephone network
between the x2 server modem and the x2 client modem.

Courier V.Everything x2 Addendum5
Controlling x2
Use the following S58 settings to control x2:
To do this
Use this command
Disable x2
S58.0=1
Force A-law mode
S58.2=1
Table 1- S58 Settings
Note: A-law is required in all countries but the United States, Canada, Japan,
Taiwan, and Hong Kong. If you are using your Courier in one of these
countries, do not force A-law mode.

6
Controlling Link Speeds with &N and &U
You can use the &N and &U commands to control link speeds. Couriers
without x2 can still use the &N and &U commands, but can only control link
speeds up to 33.6 kbps.
Controlling Link Speeds
You can use the &N and &U commands to control the link speeds of your
Courier I-modem with x2. Use the following table to determine how to use &N
and &U commands:
To limit the
Use
Highest possible connect speed
&N
Lowest possible connect speed
&U
Range of possible connect speeds
&N and &U
Table 2- Using Link Speeds
Note: The default values for &N and &U are 0. If you change these values, you will
limit the speeds at which you can connect. U.S. Robotics recommends that you do not
alter these values.
Limiting the Highest Possible Connect Speed
The &N command allows you to limit the highest possible connect speed. If a
remote modem connects to your Courier I-modem with x2 at a speed higher
than &N, your Courier I-modem with x2 will not allow it to connect.
To limit the
Use this command
Highest possible connect speed to 33600
&N=16
Limiting the Lowest Possible Connect Speed
The &U command allows you to limit the lowest possible connect speed. If a
remote modem connects to your Courier I-modem with x2 at a speed lower than
&U, your Courier I-modem with x2 will not allow it to connect.
To limit the
Use this command
Lowest possible connect speed to 48000
&U=24