ZyXEL Communications U-336S User manual

U-336S
User’s Manual
Version 2.0
(Mar. 1997)
ZyXEL
ACCESSING INTERNET & INTRANET

ii
ZyXEL Limited Warranty
ZyXEL warrants to the original end user (purchaser) that this
product is free from any defects in materials or workmanship for a
period of up to two (2) years from the date of purchase. During the
warranty period, and upon proof of purchase, should the product
have indications of failure due to faulty workmanship and/or
materials, ZyXEL will, at its discretion, repair or replace the
defective products or components without charge for either parts or
labor, and to whatever extent it shall deem necessary to restore the
product or components to proper operating condition. Any
replacement will consist of a new or re-manufactured functionally
equivalent product of equal value, and will be solely at the
discretion of ZyXEL. This warranty shall not apply if the product is
modified, misused, tampered with, damaged by an act of God, or
subjected to abnormal working conditions.
Note: Repair or replacement, as provided under this warranty, is
the exclusive remedy of the purchaser. This warranty is in lieu of all
other warranties, express or implied, including any implied warranty
of merchantability or fitness for a particular use or purpose. ZyXEL
shall in no event be held liable for indirect or consequential damages
of any kind or character to the purchaser.
To obtain the services of this warranty, please contact ZyXEL’s
Service Center, refer to the separate Warranty Card for your Return
Material Authorization number (RMA). Products must be returned
Postage Prepaid. It is recommended that the unit be insured when
shipped. Any returned products without proof of purchase or those
with an out-dated warranty will be repaired or replaced (at the
discretion of ZyXEL) and the customer will be billed for parts and
labor. All repaired or replaced products will be shipped by ZyXEL
to the corresponding return address, Postage Paid (USA and
territories only). If the customer desires some other return
destination beyond the U.S. borders, the customer shall bear the
cost of the return shipment. This warranty gives you specific legal

iii
rights, and you may also have other rights which vary from state to
state.
Copyright © 1997 by ZyXEL
The contents of this book may not be reproduced (in any part or as
a whole) or transmitted in any form or by any means without the
written permission of the publisher.
Published by ZyXEL Communications Corporation. All rights
reserved.
Note: ZyXEL does not assume any liability arising out of the
application or use of any products, or software described herein.
Neither does it convey any license under its patent rights nor the
patents rights of others. ZyXEL further reserves the right to make
changes in any products described herein without notice. This
document is subject to change without notice.
Acknowledgments
Trademarks mentioned in this manual are used for informational
purposes only.
Trademarks are properties of their respective owners.
FCC Part 15 Information
This device complies with Part 15 of FCC rules. Operation is
subject to the following two conditions:
1. This device may not cause harmful interference.
2. This device must accept any interference received, including
interference that may cause undesired operations.
This equipment has been tested and found to comply with the limits
for a CLASS B digital device pursuant to Part 15 of the FCC Rules.
These limits are designed to provide reasonable protection against
harmful interference in a commercial environment. This equipment
generates, uses, and can radiate radio frequency energy, and if not

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installed and used in accordance with the instructions, may cause
harmful interference to radio communications.
If this equipment does cause harmful interference to radio/television
reception, which can be determined by turning the equipment off
and on, the user is encouraged to try to correct the interference by
one or more of the following measures:
•Reorient or relocate the receiving antenna.
•Increase the separation between the equipment and the receiver.
•Connect the equipment into an outlet on a circuit different from
that to which the receiver is connected.
•Consult the dealer or an experienced radio/TV technician for
help.
Changes or modifications not expressly approved by the party
responsible for compliance could void the user’s authority to
operate the equipment. Shielded RS-232 cables are required to be
used to ensure compliance with FCC Part 15, and it is the
responsibility of the user to provide and use shielded RS-232
cables.
Information for Canadian Users
The Industry Canada label identifies certified equipment. This
certification means that the equipment meets certain
telecommunications network protective, operation, and safety
requirements. The Industry Canada does not guarantee that the
equipment will operate to a user’s satisfaction.
Before installing this equipment, users should ensure that it is
permissible to be connected to the facilities of the local
telecommunications company. The equipment must also be installed
using an acceptable method of connection. In some cases, the

v
company’s inside wiring associated with a single line individual
service may be extended by means of a certified connector
assembly. The customer should be aware that the compliance with
the above conditions may not prevent degradation of service in
some situations.
Repairs to certified equipment should be made by an authorized
Canadian maintenance facility designated by the supplier. Any
repairs or alterations made by the user to this equipment, or
equipment malfunctions, may give the telecommunications company
cause to request the user to disconnect the equipment.
For their own protection, users should ensure that the electrical
ground connections of the power utility, telephone lines, and
internal metallic water pipe system, if present, are connected
together. This precaution may be particularly important in rural
areas.
Caution: Users should not attempt to make such connections
themselves, but should contact the appropriate electrical
inspection authority, or electrician, as appropriate.
This digital apparatus does not exceed the class B limits for radio
noise emissions from digital apparatus set out in the radio
interference regulations of Industry Canada. The declarations of CE
marking:
This product has been approved for connection to the Public
Switched Telecommunication Network using interfaces compatible
with ITU-TSS recommendation I.420. This product complies with
the following directives:

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1. The Council Directive 89/336/EEC of 3 May 1992 on the
approximation of the laws of the member states relation to
Electro Magnetic Compatibility. (EMC Directive)
2. Council Directive 91/263/EEC of 29 April 1991 on the
approximation of the laws of the Member States concerning
telecommunication terminal equipment. (The Telecom Terminal
Equipment Directive)
3. 93/68/EEC of 22 July 1993 amending the Directives
89/336/EEC, 91/263 /EEC and 92/31/EEC.(Marking Directive)
The Council Directive 92/31/EEC of 28 April 1992 amending
directive on the approximation of the laws of the member states
relating to EletoMagnetic Compatibility.
Contacting ZyXEL
If you have questions about your ZyXEL product or desire
assistance, contact ZyXEL Communications Corporation in one of
the following ways:
•Phone: In North America call between 8:00 AM and 5:00 PM
PST at [phone]
Outside North America, you can dial [phone] EXT
252 between 8:00AM and 5:00PM Taiwan time (GMT +8:00).
•Fax: ZyXEL in North America: [phone] or Taiwan:
[phone]
•E-mail:
•Sales inquiries: [email protected] in North America.
[email protected] outside North America.
•Technical support: [email protected] in North America.
[email protected] outside North America.

vii
•Product information: Visit our site on the World Wide Web:
http://www.zyxel.com.
•FTP: Information , such as ZyXEL software and ROM updates
for North America can be found at this FTP address:
ftp.zyxel.com
For European versions and related files, use the address:
ftp.zyxel.co.at
•Postal Service: You can send written communications at the
following address:
ZyXEL Communications Corporation
6, Innovation Road II, Science-Based Industrial Park
Hsinchu, Taiwan 300, R.O.C.
or
ZyXEL Communications Inc.
4920 E. La Palma Avenue
Anaheim, CA92807, U.S.A.

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Contents
ZyXEL Limited Warranty ii
FCC Part 15 Information iii
Information for Canadian Users iv
Contacting ZyXEL vi
1Introduction 1
Unpacking Your Modem 1
Enclosed Equipment 1
Required Equipment 2
Becoming a Registered Owner 2
Modem Features 3
Standard Features 3
Intelligent Features 4
Fax Compatibility 5
Technical Specifications 5
2Installation 7
Front Panel 7
Front Panel LEDs 7
Front Panel Switches 8
Rear Panel Markings 8
Modem Connection 10
Powering Up 10
3Basic Modem Operation 13
Understanding AT Commands 13
Using the Windows 95 Hyper Terminal Program 13

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Dialing and Answering Techniques 15
Dialing using the ATD Command 15
Auto-Answer and Hook Controls 16
Making Your First Connection 16
Quick Tips when issuing AT Commands 17
Modem Result Codes 19
Viewing S Register Values 20
Changing S Register Values 20
Non-Volatile Memory 21
Storing Phone Numbers 21
Dialing Stored Phone Numbers 21
Saving Settings and User Profiles 22
Helpful Hints for PC Computers 22
Default Modem Settings for PC’s 23
ZyXEL Serial/Parallel I/O Card 23
Helpful Hints for Mac Computers 24
Special AT Command Settings for Mac 24
Mac Serial Port 24
Mac Software Tips 24
Helpful Hints for UNIX-Based Computers 25
Serial Cable 25
Basic Modem Settings for UNIX 25
Unix Software Tips 26
4LCD Panel Operation 27
LCD Panel 27
Panel Operation 28
Menu Tree 29
LED Status Screen 29
Double Arrows on The Screen 29
Dialing 30
Dial Memory 30
Storing a Number 31

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Dialing a Number 32
Manual Dial 32
Repeat Last Dial 33
Auto Answer 34
Dialing Messages 34
Panel Lock 37
V.25bis Command Set 38
Clock Options 39
RTS Options 40
Command State Options 40
Dialing from Synchronous Mode 41
Answering from Synchronous Mode 42
Auto-Answer 42
Manual Answer 42
5Leased Line Operation 43
Connecting to a Leased Line 43
Line Type Setting 43
Power Level Setting 43
Leased Line Handshaking 44
Manual Connect 44
Auto Handshake 44
Leased-Line Dial Backup 45
Dial Backup 45
Aborting from Leased-Line Operation 46
Terminating a Leased Line Connection 46
6Special Functions 47
Security Functions 47
Levels of Security 47
User Passwords 48
Remote Configuration 50

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Caller Number Delivery (Caller ID) 51
Distinctive Ring 54
Extended Distinctive Ring (EDR) 56
Setting Up EDR 57
EDR Application Example 58
7Fax Operation 61
Fax Basics 61
Modem as Fax Machine 62
ITU-T T.30 Fax Protocol 62
Fax Command sets 63
Defining the Fax Command Sets 63
Class 1 Command Set 64
Class 2 Command Set 65
Class 2.0 Command Set 71
Extended Fax AT Command Set 79
Flow Control 83
Fax Reception from a BBS 84
8AT Command Set Summaries 87
Basic AT Command Set 87
Description of ATI2 Output: 91
Extended AT& Command Set 93
Extended AT* Command Set 100
9Status Registers & Result Codes 104
S-Register Descriptions 104
Basic S-Registers "ATSn=x" 104
Extended S-Registers "ATSn=x" 105
Result Code Options 122
"ATXn" Result Code Option Table 122

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Result Code Field Descriptions 125
Connect Strings for Error Corrected Connections 125
10 Diagnostics & Troubleshooting 128
Diagnostics 128
Power-On Self Test 128
Resetting The Modem 129
Loopback Tests 130
Indicator Lights 132
Line Condition Status Display 132
Trouble Shooting 134
AT Command Set Problems 135
Command Echo Problems 136
Answer Problems 137
Dialing Problems 138
Data Transfer Problems 138
Connection Problems 139
11 Upgrading Your Modem 140
Upgrading by Flash EPROM 140
Kernel Recovery Mode 141
12 Connector Pinouts 142
Phone Jack Pinouts 142
PC Serial Port Pinouts 143
Macintosh Serial Port Pinouts 144
13 Index 146

Introduction 1
1Introduction
Congratulations on the purchase of your U-336S modem - one of
ZyXEL's premier high-performance products. The U-336S modem
is world renown for its ability to maintain ultra high speeds and
clear, quality connections while communicating around the globe.
If you do not find information on a specific topic, or if you would
like more information about a topic covered in your User's Manual,
please call ZyXEL Technical Support at 714-693-0808. Other
means of contacting ZyXEL are listed in the Contacting ZyXEL
section.
Unpacking Your Modem
Enclosed Equipment
Before you proceed further, please check all items you received
with your modem against this list to make sure nothing is missing.
The complete package should include:
•One U-336S universal modem.
•One AC power adapter (external model).
•One RJ-11 modular telephone cable.
•One warranty/registration card.
•This User’s Manual.

2Introduction
Contact your dealer or the store where you bought the modem if
anything is missing. Check the modem for shipping damages. If you
find any damage, contact the shipping agency immediately.
Retain shipping and cushioning materials for future storage or
shipping needs.
Please direct any additional questions about damaged or missing
materials to your dealer or distributor, or contact ZyXEL customer
service using the information on page vi.
Required Equipment
In addition to the ZyXEL modem you just purchased, you must
have the following equipment to operate your modem:
•Computer terminal.
•Available PC serial port with a high-speed 16550 UART.
•Standard "straight-through” RS-232 cable (pins 1-8, 20, 22).
•Available telephone jack.
•Available AC wall outlet.
•Telephone line from your telephone company (dial-up or leased
line).
•Data and fax communication software.
Becoming a Registered Owner
Complete the pre-addressed Warranty Registration Card and place
it in the mail. Registered owners will receive future product
information and update announcements. Warranty registration is

Introduction 3
not necessary for product repair/or replacement, save your dated
invoice as proof of purchase.
Modem Features
No other 33.6 Kbps modem gives you so much for so little. Your
modem is equipped with an array of standard and ZyXEL-famous
Intelligent features designed to make your data communications
faster, easier, and more convenient.
Standard Features
•Ultra-high speed modem supports V.34bis for 33,600bps and is
backwards compatible.
•Operates in all environments including: Windows 95, DOS,
Windows, Macintosh, OS/2, UNIX, Novell, Amiga, and IBM
AS400/RS6000.
•V.42 and MNP 4/3 error correction.
•V.42bis and MNP 5 data compression.
•DTE serial interface with speeds up to 460.8Kbps.
•20 x 2 LCD display.
•10 LED indicators.
•Extended AT command set with V.25bis.
•Operates on 2-wire dial-up or 2/4-wire leased line.

4Introduction
Intelligent Features
•Automatic data, fax and voice call detection allows you to use a
single telephone line to handle all three types of calls.
•Asynchronous and synchronous modes for reliable serial data
communication.
•Fast retrain with automatic fall-forward and fall-back. Your
modem will automatically fall back to lower speeds when
communicating with slower modems and when encountering
unstable or variable line conditions.
•Call-back security and password protection restricts access to
authorized callers only.
•Caller ID identifies incoming calls before you answer (you must
subscribe to this service through your telephone company in
order for your modem to identify callers).
•Distinctive ring detects data, fax and voice calls (this feature
requires communication software that supports distinctive ring,
such as ZFAX).
•Remote configuration capability.
•EDR (extended Distinctive Ring).
•Flash EPROM memory lets you easily upload new firmware,
providing you with easy access to new features.
•ZyXEL exclusive Kernel Recovery Mode for no hassle recovery
from failed flash uploads - no factory repairs.

Introduction 5
Fax Compatibility
•EIA Class 1, 2, and 2.0 Fax commands.
•ITU-T V.17 G3: up to 14,400bps.
•ITU-T V.29 G3: up to 9,600bps.
•ITU-T V.27ter G3: up to 4,800bps.
•ZyXEL Fax AT commands.
Technical Specifications
•Operating mode: auto-dial/answer.
•Flow control: software XON/XOFF or hardware CTS/RTS.
•Configuration settings: software programmable with non-
volatile memory for phone number/profile storage.
•Diagnostics: self test, analog loopback (with self test), digital
loopback, and remote digital loopback (with self test).
•Dialing type: tone/pulse dialing.
•Line interface: 2-wire dial-up or 2/4-wire leased line.
•Call progress monitoring: dial tone, busy, and ring back
detection.
•Audio Monitor: programmable volume control.

6Introduction

Installation 7
2Installation
This chapter describes the panel function and installation procedure
for the U-336S.
A shielded RS-232 cable is required to ensure compliance with
FCC Part 15, and it is the responsibility of the user to provide and
use a shielded RS-232 cable. Make sure your installation site is
clean and well ventilated. The ventilation slot of your ZyXEL
modem located on the sides and bottom should not be covered and
should allow free movement of air.
Front Panel
The figure below shows the front panel of the U-336S. There are
10 LED indicators, a 20 x 2 LCD display, and four key switches.
Figure 2-1Front Panel
Front Panel LEDs
PWR Power ON indicator, lights up when your modem is turned
ON.
OH Off-Hook indicator, lights up when your modem is in data
mode or off-hook. It goes out when your modem is in talk
mode or on-hook.

8Installation
AA Auto-Answer indicator, lights up when your modem is in
the Auto Answer Mode; flashes when modem rings. In error
control mode, it flashes when retransmitting.
DTR Data Terminal Ready indicator, lights up when your DTE or
computer indicates that it is ready to begin communication.
DSR DTE mode: Data Set Ready Indicator, lights up when the
modem is ready for communication.
TXD Transmit indicator, ON when your DTE/computer transmits
data on the serial port.
RXD Receive indicator, ON when your DTE/computer receives
data on the serial port.
CD Carrier Detect indicator; lights up when a valid carrier is
detected present on the line.
RTS DTE mode: Request To Send indicator; indicates the signal
status of RS232 signal RTS from DTE. RTS is used for
hardware flow control in asynchronous data transmission.
CTS DTE mode: Clear To Send indicator; lights up when modem
can accept data for transmission. It indicates the signal
status of RS232 signal CTS.
Front Panel Switches
The four arrow keys are for panel operations, allow intuitive menu
tree operation and display modem status. Refer to Panel Operation
on page 28 for details of menu key operations.
Rear Panel Markings
The U-336S rear panel is shown below: