ZyXEL U-1496, U-1496E, U-1496B, U-1496R, U-1496P User Manual

ZyXEL

U-1496 Series Modems

User’s Manual

Copyright 1994-1997 by ZyXEL Communications Corp.

Chapter One - INTRODUCTION

THE U-1496 SERIES UNIVERSAL MODEMS
The U-1496 series of high-speed modems feature five base models.

They are:
U-1496

External stand alone model with 20 x 2 LCD display and menu
control.
Also called U-1496S. Includes 2/4-wire leased line support.

U-1496E
External stand alone model with LED status indicators. 2-wire
application only.

U-1496B
PC internal card version.

U-1496R
Rack mount modem card version. Up to 16
U-1496Rs can be housed in
a RS-1600 rack with central panel control and 20 x 4 LCD display.

U-1496P
A portable model, particularly suitable for cellular data
communications.

There are also models with a plus (+) suffix, such as U-1496E+,
U-1496R+, and U-1496B+. These plus versions have a faster
processor and more memory space to support the ZyXEL 19200 bps
high-speed mode, advanced voice capability, and future updates
with more enhanced features.

The basic features, functions, and operation of the plus versions
are the same as those of the normal version. We do not
specifically mention the plus version in this manual unless there
are functional or operational differences. The U-1496 LCD model
is always a plus version.

HOW TO USE THIS MANUAL
This manual describes the use of all models in the U-1496 series,

the U-1496, U-1496E, U-1496B, U-1496P, and U-1496R. Usually, this
manual describes the operation of the U-1496, the model with the
largest set of functions. If a description does not apply to a
certain model, you may skip the description.

The manual is structured into roughly 5 sections.
The first section comprises chapters 1 through 3. It gives a

basic overview of the U-1496 series modems' features, introduces
some basics of modem operation for novice users, and explains the
installation of the different models of the U-1496 series
including the U-1496B PC-card. Please note that the COM port and
interrupt number must be properly chosen, before the U-1496B can
be installed.

The panel operation of the U-1496 is described in Chapter 4 and

5. The U-1496 has an LCD display menu control panel. The rack
system has a central menu control panel similar to that of the
U-1496. Users of the other models should consult the equivalent
AT command sections listed for each of the panel operations.

The third section, chapters 6 through 8, provides an overview
of the settings and commands which are available in the U-1496
series.

Section four comprises chapters 9 through 17 and describes many
special functions of the U-1496 series modems in detail,
including data compression, synchronous and lease line operation,
remote configuration, caller ID, cellular mode, fax send and
receive, voice mail, network management, and diagnostic features.

Section five is the trouble-shooting and special advice section.
Here you find additional information on how to use a U-1496
series modem with your computer, and some hints and tips
relating to a number of communication software applications.

A glossary, several appendices with technical details and
information on standards, and a thorough index complete this
manual.

The RS-1600 rack system comes with a supplemental User's Guide
describing the use and installation of the rack system. The
Network Management System comes with a separate manual detailing
its installation and usage.

Compatibility
ZyXEL U-1496 series modems are high performance universal

modems capable of transmission speeds up to 19.2 Kbps full-duplex
on a 2-wire dial-up line. Universal compatibility covers a broad
range of CCITT and BELL standards, and provides data compression
and error free transmission.

Various operation modes that can be achieved are as follows:
Bit rate Baud rate Modulation Carrier

(+/-0.01%) (+/-0.01%) Freq
bps baud Hz
ZyX19200 19,200 2743 256TCM 1800
ZyX16800 16,800 2400 256TCM 1800
V.33 14,400 2400 128-TCM 1800

V.33 12,000 2400 64-TCM 1800
V.32bis 14,400 2400 128-TCM 1800
V.32bis 12,000 2400 64-TCM 1800
V.32bis 7,200 2400 16-TCM 1800
V.32 9,600 2400 32-TCM 1800
V.32 uncoded 9,600 2400 16-QAM 1800
V.32 4,800 2400 4-DPSK 1800
V.29 9,600 2400 16-QAM 1700
V.29 7,200 2400 8-QAM 1700
V.29 4,800 2400 4-DPSK 1700
V.27ter 4800 1600 8-PSK 1800
V.27ter 2400 1200 4-DPSK 1800
V.23 1200/75 1200/75 FSK
V.23 600/75 600/75 FSK
V.22bis 2,400 600 16-QAM 1200 Orig. 2400 Ans.
V.22 (BELL 212A) 1,200 600 4-DPSK 1200 Orig. 2400 Ans.
V.21 300 300 FSK
BELL 103 300 300 FSK
G3 Fax implemented according to T.30, V.17,V.29 and V.27ter.
Cellular Modes ZyXEL proprietary cellular modes, 14400 bps to
2400 bps speed range.

1800 Hz guard tone for V.22bis/V.22 answer mode, 6 dB below
data signal level.

Note: V.33, V.29, V.27bis, V.27ter and V.26bis are only available in
models U-1496 and U-1496R for 4-wire leased line operation. The
other operation modes are common to all models.

THE U-1496 SERIES STANDARD FEATURES
Synchronous/Asynchronous operations for external stand alone

models and rack mount model.
Asynchronous operations for PC internal card model.
MNP class 4/5 error correction/data compression.
V.42/V.42bis error correction/data compression. V.42 with

selective reject feature.
Extended AT command set.
V.25bis async/sync command set.
Operate on 2-wire dial-up line or 2/4-wire leased line. (4-wire

leased line on U-1496 and U-1496R only.)
Auto-dial/answer and manual originate/answer.
Tone/Pulse dialing.
Dial tone, busy, and ringback detection.

Programmable speaker volume control.
Non-volatile memory storage.
Remote configuration.
Security call back.
Caller ID detection.
Distinctive ring detection.
Extensive Status reports.
Diagnostics available for:

Modem full self test
Analog loopback (w/ self test)
Remote digital loopback (w/ self test)
Digital loopback

XON/XOFF or CTS/RTS flow control.
Line status monitoring available for: (U-1496 and U-1496R)

Signal-to-noise ratio
Receive signal level
Frequency offset
Phase jitter
Retrain granted
Retrain requested
Round trip echo delay
Carrier loss counter
Rate change granted
Rate change requested
Blocks retransmitted
Blocks in error

20 X 2 LCD display and directional keypads. (On U-1496 model
only, 20 x 4 on rack panel.)

G3 Fax send and receive capability with speeds up to 14400 bps.
Fax-Polling / Fax-Grouping.
Automatic detection of data or fax call.
Digitized voice capability with speech compression.
Special cellular modes for data communications through cellular

link.
Full two-year warranty.

BEFORE YOU GET STARTED
Before you proceed further, please check to see if you have all

the necessary materials from the shipping package and make sure
nothing is missing. The complete package should include:

one (1) U-1496 series universal modem
one (1) power adapter pack (stand alone model only)
one (1) RJ11 telephone cable
one (1) JM8 leased line cable (U-1496 only)
one (1) U-1496 series user's manual
one (1) ZFAX 3.5" floppy disk
one (1) warranty/registration card
one (1) Quick Reference card

Contact your dealer or the store where you bought the modem if
anything is missing. After you unpack the modem,
please check for shipping damages. If you find any damage,
contact the shipping agency immediately.

Please retain the shipping carton 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 to factory with
address listed on your warranty card.

HOW TO BECOME A REGISTERED OWNER
Simply fill in the registration card and mail it to the address

found on the reverse side of the card. Registered owners will
receive future product and update information. You don't have to
register to receive warranty service. A dated invoice as proof of
purchase along with the warranty card are sufficient.

WHAT YOU NEED TO HAVE
You need the following equipment to operate your modem:
Computer/Terminal with communication software (e.g,. PC with

Windows Terminal).
RS-232 serial cable (not supplied with modem).
Note: If you bought the internal PC card, you don't need a serial

cable.
A telephone line from your telephone company (dial-up or leased

line).

COMMUNICATION SOFTWARE

Communication software controls the modem connected to the
computer and directs data to and from the modem. For most cases
in the PC environment, the modem is used in an asynchronous mode
and the software controls the modem by the AT commands. ZyXEL
modems support the extended AT command set and are compatible
with most communication software packages. However, there are
some unique features in the ZyXEL modem and there are a few
unique commands to control them. Some communication packages
need a "modem data file" to tell it which commands and features
the modem supports. The floppy disk included with your modem
package features sample data files for some popular communication
software packages.

CONNECTING TO YOUR PHONE
If you would like to use a single phone line for voice and

modem connections, remove your phone cable from the RJ11 junction
box and plug one end of the RJ11 cable (supplied with modem) into
the socket on the phone, then plug the other end of the cable to
the rear panel of the modem labeled "DIAL-UP LINE" or "WALL".
Finish by plugging in your phone cable to the rear panel of the
modem labeled "PHONE". Please refer to the illustration in Fig.
3-3.

DIAL-UP OR LEASED LINE
The U-1496E and U-1496B can connect to 2-wire dial-up or leased

lines only. The U-1496 and U-1496R offer you a choice of
connecting to 2-wire dial-up line (more commonly known as public
lines) and 2/4-wire leased lines. To use the U-1496 on a leased
line, you must order and install a USOC JM8 jack. You must also
specify 4-wire operation without TEK leads for the wiring option.
When setting up a pair of modems for leased line point-to-point
operation, one must be configured for originate mode and the
other for answer mode. Both RJ11C and JM8 cables are supplied for
your convenience.

Chapter Two - MODEM AND FAX BASICS

This chapter is intended for those who want to know the details behind modem and fax
operations; what's going on behind the scenes. In addition to basic modem and fax terminology,
this chapter helps users understand and use the available features. Experienced modem and
fax users may wish to skip this chapter.

WHAT IS A MODEM
Modem is a compound word of MOdulator and DEModulator. A modem is

used for computer communications. Refer to Fig. 2.1 for a
standard modem setup and application. A modem translates computer
data to analog signals (modulation) that can travel through the

telephone network and reach the other modem. The remote modem
translates the analog signal received back into data
(demodulation) and sends the information to the receiving end
computer. Modems are telephones for computers, what
they use to talk to each other.

((*MODE-02*; Modem as used in computer communications))
WHAT ARE DTE AND DCE
DTE and DCE are terminologies used in data communication. DTE stands for Data Terminal

Equipment and DCE stands for Data Circuit terminating Equipment (Data Communication
Equipment). Referring to Fig. 2.1, the computer or terminal is the DTE and the modem is the
DCE.

WHAT IS RS-232C OR EIA-232D
RS-232C is the Recommended Standard (RS) by the Electronic

Industries Association (EIA) defining the serial communication
interface between a DTE and a DCE. The most commonly used
revision is the "C" revision. For "D" revision, it changes the
prefix to EIA. Except for a few added, but not commonly used
signals, there is no practical difference between the "C" and "D"
revisions. RS-232C is equivalent to CCITT V.24 and V.28.

WHAT IS A SERIAL PORT
A serial port is the serial data connector together with its

internal circuit on the DTE or DCE with electrical and mechanical
characteristics according to RS-232C. Since some signals are
going from the DTE port to DCE port, and some signals are going
in the other direction, the signal pin is a transmitter on one
port and a receiver on the other. The DTE serial port is
different from the DCE serial port in terms of signals on the
connector pins. There are also mechanical differences in terms of
male or female connectors.

SERIAL RS-232C CABLE
A serial RS-232C cable is used to connect a DTE port to a DCE

port. A normal RS-232C connector has 25 pins and a normal RS-232C
cable has 25 wires. Many signals in the RS-232C are not used in
common applications and a 9-wire RS-232C cable is sufficient in
most applications. The PC-AT's serial port has only 9 connector
pins, eliminating the unnecessary pins.

SYNCHRONOUS AND ASYNCHRONOUS COMMUNICATION
There are two kinds of serial data communication. One is called

synchronous and the other is called asynchronous. In synchronous
communication, data is transmitted and received bit by bit and is
timed by an accompanying clock signal. In asynchronous
communication, data is sent character by character (or octet by
octet), the idle time between characters is variable. No clock

signal is sent; character timing is recovered from the data
itself.

A PC's COM1 and COM2 are asynchronous serial ports. Most PCs' and
Unix systems' serial data communications are asynchronous. The
serial data communication on an IBM mainframe or mini is
synchronous.

WHAT IS UART
UART (Universal Asynchronous Receiver Transmitter) is the device

used in a DTE or DCE for asynchronous data reception and
transmission. The normal UART device used in PCs is of the
NS16450 type. For high-speed serial data receiving (38400 bps and
up), the PC may not serve the UART fast enough and data may get
lost. In this case, a UART with data buffer is needed, such as
the NS16550A type.

MODEM STANDARDS AND SPEEDS
The CCITT (Comite International Telegraphique et Telephonique, now called

ITU-TSS (International Telecommunications Union - Technical Standardization Sector), is the
international standard-making body for telecommunication. They draft "recommendations". The
recommendations they made for modem applications have a "V" prefix and are called V-series
recommendations. The commonly used CCITT standards for 2-wire dial-up line are:

V.32bis 14400/12000/7200 bps
V.32 9600/4800 bps
V.22bis 2400 bps
V.22 1200 bps
V.21 300 bps
V.23 1200/75 bps

Note: bis is the French word for second.
In the USA, Bell Systems used to create the de facto standard

such as Bell 212A for 1200 bps modems and Bell 103 for 300 bps
modems. Everyone is following the CCITT standard now for newer
and higher speed modems.

ZyXEL U-1496 series modems support all the above mentioned modem
standards and are compatible with existing modems.

TYPE OF TELEPHONE LINE
The commonly used phone service is a 2-wire dial-up line. Only

two wires connect the modem to the phone company's central
office. The same two wires are used for DC current feeding,
ringing, dialing, on/off-hook monitoring, and signal transmission
in both directions. This is the type of phone service most people
have in their home or office. Since the same two wires are used
for both transmitting and receiving signals, an echo of the
transmitting signal will also be received and it is the modem
receiver's task to remove the echo before demodulation.

A leased-line phone service is also available from phone companies in a 4-wire form. Here the
transmitting and receiving signal each uses a separate 2-wire pair and thus no echo problem will
result. Normally, no DC current feeding, ringing, or dialing function is provided on a leased line.

There is also the case of a 2-wire leased line which is a
permanent 2-wire connection.

INTELLIGENT MODEM
In the old days, modem functions, settings, and operations were

simple and everything was controlled by manual switches, either
internal or external, or by wire-strapping settings. No computer
control was provided.

An intelligent modem has all its functions, including dialing and
answering, controllable by the computer or terminal it is
connected to, through the same RS-232 serial interface used for
data connection.

An intelligent modem operates in one of two states - the command
state and the data state. In command state, the modem interprets
data received from the serial interface as "commands" and send
back an action result in response. In data state, the modem
modulates the data received from the serial interface and sends
the demodulated data to the serial interface as received data.
The user needs to know whether the modem is in the command state
or data state and how to switch it.

AT COMMAND SET
The AT command set is the industry de facto standard used to

control a modem in command state. It got its name from the fact
that every command line has a prefix "AT".

AT commands were first used in the Hayes Smartmodem (R) and hence
adopted by other modem manufacturers and communication software
writers. The original set of AT commands such as dialing,
answering, etc., is used by everyone else and is standardized.
The AT command set is extended by each modem manufacturer for
control of ever-increasing modem functions and capabilities. This
"extended" or "enhanced" command set is not standardized
whatsoever.

The AT command set is used only with an asynchronous serial data
interface.

ZyXEL has defined a set of extended AT commands to support many
of its unique functions and features.

V.25bis COMMAND SET
V.25bis is a set of auto-dialing commands defined by the CCITT.

V.25bis supports both synchronous and asynchronous data

interfaces and finds most of its use in Europe and IBM mainframe
or mini environments which use synchronous communication.

ERROR CORRECTION
In synchronous data communication, data is checked and corrected

in the host by the so called "link layer protocol" to ensure data
integrity. Normally, no data checking is provided in the host for
asynchronous data communication.

Nowadays, intelligent modems incorporate error correction
protocols inside the modem for asynchronous data communication
and it is transparent to the host. The modem packs the
asynchronous data characters into blocks, the data blocks are
error checked at the remote end and the erroneous block is
retransmitted.

The commonly used error correction protocols are MNP (R) and V.42
protocols.

DATA COMPRESSION
Intelligent modems use redundancy removing methods to reduce the

number of data bits actually sent for asynchronous character
transmission. The full character data is recovered at the other
end, thus the total throughput of the modem data transmission is
increased.

The commonly used data compression protocols by modems are MNP
(R) class 5 and V.42bis.

Data compression works on redundancy removing and its efficiency
is both algorithm and data dependent.

MNP (R) PROTOCOLS
MNP (R) (Microcom Network Protocol) is a set of protocols first

introduced by Microcom, Inc., and later used by many modem
manufacturers. It consists of many classes. Classes 1 to 4 are
for error correction, and class 5 is for data compression. MNP
class 1 and 2 are obsolete. Normally class 4 is used for error
correction and it uses class 3 internally.

MNP class 5 is a data compression protocol with a maximum
efficiency of 2 to 1. MNP-5 is used with MNP-4 for error
correction.

V.42bis AND V.42
V.42bis and V.42 are data compression and error correction

standards set by the CCITT. V.42bis has a better data compression
efficiency than MNP-5 and is a more advanced data compression
scheme.

V.42bis is used with V.42 for error correction.

XMODEM, YMODEM, AND ZMODEM
These are file transfer protocols used by the host (e.g., the

communications program in the PC). It does error checking and
ensures data integrity of the file transferred. Some variations
of these protocols also appear, like Xmodem-1k, Ymodem-G, etc..

The "G" flavors of protocols do not include error checking. They
allow very high throughput rates, but can be safely used only
when the modems use MNP4 or V.42 error protocols.

Whenever possible, we recommend the use of Zmodem for added
security and high flexibility. Consult your communications
program manual for more information on transfer protocols.

FAX AND FACSIMILE
Fax is the abbreviation for facsimile. There are four major parts

in a normal facsimile machine, the scanner, encoding and decoding
device, modem, and printer. Before a page can be sent it is first
scanned, the bit-mapped data is encoded with data compression,
then it is transmitted across the phone line by an internal modem
module. The remote facsimile receives the data with its internal
modem, decodes it back to bit-mapped image data and prints it on
paper, normally with a thermal printer on thermal sensitive
paper.

FAX CARD
A fax card is an internal plug-in card which must be specifically

designed to fit into your type of computer. It has the modem
function of a facsimile machine. A computer loaded with fax
software can send or receive faxes through a fax card. The
computer is used as the input and output parts of a facsimile
machine and the fax card is used as the transmit/receive part and
may also do the encoding/decoding function, depending on the
design. The computer controls and communicates with the fax card
through a set of proprietary hardware and software interfaces
which are different for each fax card manufacturer.

MODEM AS A FAX
Normal modems can also be designed to include the fax

transmitting and receiving function, as does a fax card, since
the modem's interface with the computer is the standard serial
RS-232 interface. This interface will be used for both modem and
fax operations. With the data throughput of a serial RS-232
interface being limited, only compressed fax image data can be
carried through this serial interface. Fax image coding and
decoding must be done in the computer. Modem/Fax, also called
faxmodem, can be either an external stand alone unit or an

internal PC plug-in card. External stand alone units can be
connected to any computer with a standard RS-232 serial port.
This computer need not be a PC.

EIA CLASS 2 FAX COMMAND
The EIA class 2 fax command is a set of AT fax commands defined

by EIA/TIA (Telecommunications Industry Association) for
controlling faxmodems from a computer through the serial RS-232
interface. Faxmodems and fax software supporting this standard
will work together. The problem is that there are several
revisions of this standard. Implementations conforming to
different revisions may not work together.

AUTODETECTION OF FAX OR DATA CALL
Fax and data modems have different handshaking signal sequences

at the beginning of a call as specified by the CCITT. It is
possible to automatically detect whether an incoming call is from
a modem or a fax device by testing and recognizing its initial
handshaking sequence. A modem with this capability can make a
computer process both data and fax calls on the same phone line.
An example is that a BBS (Bulletin Board System) can also receive
faxes. ZyXEL modems can automatically detect data and fax calls.
ZyXEL also includes a fax receiving and printing program to allow
a BBS to receive faxes and print them out in the background.

CALLER ID
Normally called Caller Number Delivery (CND), this is a service

available from phone companies in several parts of USA and some
other countries. With this service, the phone company sends
calling party information along with ring signal to the called
party. The major part of this information is the telephone number
of the calling party or caller ID. ZyXEL modems can detect and
report caller ID.

DISTINCTIVE RING
This is a service available from some phone companies in some

areas of the USA and in other countries. You can have several
phone numbers on the same subscriber phone line. The phone
company sends a different ring signal for each phone number
assigned to the same line. You can have your phone equipment
answer only a certain type of ring corresponding to a certain
phone number. ZyXEL modems can be set to answer on one or a
combination of four types of ring signals. The problem is that
every country may have a different specification for different
ring types.

DIGITIZED VOICE
Modems with digitized voice capability can digitize an incoming

voice message with the computer storing it as a file. The modem

can also playback a recorded digital voice message either locally
or to the line as an announcement.

Digital voice messages need speech compression to reduce the storage requirement. This
speech compression is done in real time by the modem and it does the decompression during
playback. A simple voice capability using an ADPCM (Advanced Digital Pulse Coded
Modulation) algorithm can reduce the speech data rate to 1/2 or 1/3 of the original rate. We call
it advanced voice capability when a compression scheme can reduce the speech data rate even
further with advanced algorithms like CELP (Code Excited Linear Prediction).

CELLULAR MODEM
A cellular modem is a data modem that can be used on the analog

cellular mobile phone system. With the rising popularity of
notebook computers this has an increasing importance for people
on the move.

There are two kinds of phenomenons in the cellular mobile phone
system that are particularly bad for modem data communications.
One is called cell hand-off, meaning that a cellular phone is
instructed to change the radio link from one cell site to another
when travelling across a site boundary. The radio link will be
temporarily interrupted and most modems will retrain or even hang
up. Instructing a cellular phone to change transmitting power
will cause similar problems. The other particularly annoying
phenomenon is multipath fading. Here, a moving cellular phone
will experience periodical fading or drop-out of the radio
signal. This causes high data error rates and low throughput.

Communication protocols like MNP10 do not do anything to improve
the physical layer of data communication robustness and cannot
really help in cellular data communication.

ZyXEL developed cellular modes for its modems using its
proprietary data pump that conquers the cell hand-off and
multipath problems. The V.42 link layer protocol with selective
reject greatly improves data file transfer throughput.

AUTOMATIC REDIAL / CALL HUNTING
Most modems will automatically redial a telephone number several

times, if a connection could not be established on the first try.
The modems of the U-1496 series also offer the ability to do
cyclic redials of a set of up to ten different numbers.

MODEM AND LEGAL MATTERS
In some countries the PTT authorities require modems to conform

to a set of specific rules, e.g., restricting the behavior of
modems during automatic redial. Modems must receive an official
approval within those countries to be used legally. ZyXEL already
has provided specifically designed models which have received
such an approval. Check with your PTT authority to find out about
existing restrictions.

Chapter Three - MODEM INSTALLATION

This chapter describes the panel function and installation guide
for model U-1496, U-1496E, and U-1496P. The U-1496R comes with
its own installation guide. The installation guide for U-1496B is
in Chapter 18.

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.

U-1496 FRONT PANEL
Fig. 3-1 shows the front panel of the U-1496. There are 6 LED

indicators, a 20 x 2 LCD display, and four key switches.
((MODE-03))

U-1496 FRONT PANEL INDICATORS
LED Indicators
PWR Power ON indicator, lights up when U-1496 is turned ON.

OH Off-Hook indicator, lights up when U-1496 is in data mode or
off-hook. It goes out when U-1496 is in talk mode or on-hook.
AA Auto-Answer indicator, lights up when U-1496 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.
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.

U-1496 FRONT PANEL SWITCHES
The four arrow keys are for panel operations. They allow

intuitive menu tree operation and status display. Refer to
Chapter 4 for the detail of menu key operations.
((MODE-04))

U-1496 REAR PANEL MARKINGS
Fig. 3-2 shows the U-1496 rear panel. The following explains the

connectors and switch on the rear panel.
POWER Power switch, turns the modem ON or OFF.
POWER JACK Input terminal for power adapter.

LEASED LINE Leased-line JM8 terminal jack, for connection to a
2/4-wire leased line. DIAL-UP LINE Dial-up line RJ11 terminal
jack, for connection to a 2-wire dial-up line. PHONE Telephone
line RJ11 terminal jack, for connection to a telephone set.
EIA-232D Serial port DB25S connector, for connection to the
serial port of a DTE (computer/terminal). Pin assignments are
listed in Appendix A for your reference.
The signal-pin assignments on RJ11 and JM8 phone jacks are listed
in Appendix B.

MODEM CONNECTION
When you connect your U-1496 to the power line, make sure you

only use the ZyXEL power adapter that is supplied with this unit.
Use of another adapter may not allow your modem to operate and
could result in serious damage to the unit. This adapter is rated
for direct connection to an AC power outlet and has a 2-meter
cord. Connect the U-1496 as shown in Fig. 3-3. Connect U-1496E in
the same way, except there is no Leased Line jack. A 2-wire
leased line can be connected to the DIAL-UP LINE jack for U-1496E
and U-1496P.

((MODE-05))
If leased line is not used, simply leave the connection out.

There are no DIP switches or configuration settings that you need
to worry about. The U-1496 comes factory pre-set and allows you
to fully configure the modem from the LCD display after you turn
the power on. User configurations are also conveniently stored in
user selectable non-volatile memories and can be recalled as
often as needed.

POWERING UP
Once the U-1496's power switch is turned ON, the U-1496 will

perform a series of diagnostic tests while a message is shown on
the LCD panel. For a more detailed description of these
diagnostic tests, please refer to Chapter 17 Diagnostics.

After performing the diagnostic tests, your U-1496 will display
the current modem settings on the front LCD panel as shown in
Fig. 3-4. Your U-1496 modem is now ready for use.
((MODE-06))

U-1496E FRONT PANEL
Fig. 3-5 shows the front panel of the U-1496E. There are 12 LED

indicators and two switches.
((MODE-07))

U-1496E FRONT PANEL INDICATORS

LED Indicators
HS High Speed indicator, lights up when modem is in V.32 or
V.32bis mode. Dialing indicator, flashes one second on and one
second off when dialing. Retrain indicator, flashes half second
on and half second off when modem is in retrain.
AA Auto-Answer indicator, lights up when modem is in the Auto
Answer mode; flashes when modem rings.
CD Carrier Detect indicator, lights up when a valid carrier is
present on the line.
OH Off-Hook indicator, lights up when modem is in data mode or
off-hook. It goes out when modem is in voice mode or on-hook.
DTR Data Terminal Ready indicator, lights up when the DTE or
computer indicates that it is ready for communication.
DSR Data Set Ready indicator, lights up when modem is ready for
communication.
CTS Clear To Send indicator, lights up when modem can accept
data for transmission.
TXD Transmit Data indicator, lights up when the DTE/ computer is
transmitting data on the serial port.
RXD Receive Data indicator, lights up when the DTE/computer is
receiving data on the serial port.
EC Error Control indicator, lights up when modem is operated in
an error control mode like MNP-4 or V.42. Data compression mode
(V.42bis or MNP 5) implies error control mode. Retransmission
indicator, lights up when retransmitting.
SQ Signal Quality indicator, lights up when signal quality is
good; flashes when it is on margin. At power-on it flashes to
indicate error, refer to Chapter 17 for details.
TST Test indicator, lights up when modem is in a test mode.

U-1496E FRONT PANEL SWITCHES
VOICE/DATA
A toggle switch that toggles the modem on-line (off-hook, DATA

mode) or off-line (on-hook, VOICE mode, the telephone set is
connected to the line). If the S35 bit 4 is set (S35.4=1),
pressing this switch will make the modem go off-hook and dial the
default number.
ANS/ORG

A locked switch, it determines if the modem is in originate mode
or answer mode when the modem goes off-hook by toggling the
VOICE/DATA switch. Locked up position means answer mode and
locked down position means originate mode.

Note: This switch determines on-line mode only when manual
off-hook. ATD or ATA command will automatically determine the
mode.

U-1496E REAR PANEL MARKINGS
Fig. 3-6 shows the rear panel of U-1496E. The rear panel markings

are the same as those of the U-1496 in Fig. 3-2 except that

U-1496E does not have the leased line jack.
((MODE-37))

Refer to U-1496 rear panel description and modem connection for
U-1496E's rear panel explanation.

U-1496P FRONT PANEL
Fig. 3-7 shows the U-1496P front panel. The following explains

the connectors and indicator on the front panel.
((Figure 3-7: U-1496P FRONT PANEL - redraw))
POWER Power jack connector for power connection.

The U-1496P uses a DC 12V power source.
You can use either the attached AC power adaptor
or car battery through the cigarette lighter cable as the power
source.
LED A dual color LED for status indication,
Green On: indicates power on idle state.
Green flash at

0.5 Hz: indicates dial state

1.0 Hz: indicates handshake state
20 Hz: indicates data state
2 sec ON/4 sec OFF: indicates ringing.
Red ON when in data state: indicates bad signal quality.
Red and Green both FLASH: the number of flashes indicate
the error code of power-on selftest.
LINE RJ-11 phone jack for 2-wire dial-up line
connector, connect to wall outlet jack or a cellular phone
adaptor.
PHONE RJ11 phone jack for connection to a
telephone set.

U-1496P REAR PANEL
Fig 3-8 shows the U-1496P rear panel. The following explains the

connector on the rear panel.
((Fig 3-8: U-1496P REAR PANEL - redraw))
EIA-232D Serial port DB25S female connector, for connection to

the serial port of a DTE (computer/terminal). Pin assignments are
listed in Appendix A for your reference. This serial port
connector supports both synchronous and asynchronous
communication.

MODEM CONNECTION
((Fig 3-9: U-1496P CONNECTION for cellular communication -

redraw))
Fig 3-9 shows the modem connection with U-1496P. There are three

ways of connecting power to your U-1496P. Select the most

convenient method. The cellular adaptor available from certain
vendors will adapt a specific cellular phone unit to a normal
2-wire phone interface for the modem connection. It provides dial
tone and ring signal to the modem. Because of the absence of a
cellular interface standard, a special cellular adaptor is needed
for each specific cellular phone.

((Here we will include the information of chapter 18; U-11496B installation; so that we have all
installation procedures in one chapter. This cleans up stuff a little bit.))

Chapter Four - QUICK START

This chapter tells you how to dial and answer on a modem. If you
use this modem with a PC, you probably don't need to worry about
modem settings. The factory default may be just right for you.
Connect the modem according to instructions in Chapter 3, install
the communication software on the PC, make the modem dial as
instructed in this chapter, and you're all set.

This chapter also familiarizes you with the panel operation of
the U-1496. This modem comes with a menu driven 20 x 2 LCD
display. All functions of the modem are displayed and selectable
from this menu. This chapter will also familiarize the user with
the menu tree structure. It properly categorizes the modem
operations. U-1496E and U-1496B modem users can also consult the
U-1496's panel menu operations, but use the equivalent AT command
listed in this chapter instead.

LCD PANEL
The U-1496's commands, options, and parameters can be set,

changed, and viewed from the front panel or viewed and changed
through AT commands by the computer or terminal connected to the
modem. We will discuss panel operations in this chapter with
reference to equivalent AT commands.

Once powered up, the U-1496 goes into the Idle Screen (if not
leased line selected). It then waits for commands from a
PC/terminal or any key pad operation from the front panel. Refer
to Fig. 3-4, there are four ON SCREEN BUTTONS:

D Dialing menu.
R Redial last number.
O Originate mode on-line.
A Answer mode on-line.

Also, the status and current settings are displayed:
Link Option V.32bis

Link Speed 14400 bps
Error Control V.42 (implied by V.42bis)
Data Compression V.42bis
Line Type Dial-up line
Data Format Asynchronous
DTE Speed 57600 bps

PANEL OPERATION
Four arrow keys manipulate the menu tree:
Left/Right arrow keys used for horizontal item selection and

options selection.
Up arrow key also called the MENU key, is used for vertical
menu selection and is used to access the previous menu. The up
arrow key also serves as a quit command when you want to stop the
current action.
Down arrow key also called the ENTER key, is used solely to
register the chosen selection and is very similar to the CARRIAGE
RETURN key or ENTER key on a standard keyboard.

MENU TREE
Fig. 4-1 shows the menu tree structure. There are two main menu trees. One is the

CONFIGURATION menu, the other is the DIAGNOSTIC menu. Fig. 4-2 shows the submenus
under the CONFIGURATION menu. In Fig. 4-1, there is one idle screen and four data state
screens. In data state, screen (1) to (4) can be accessed by pressing the left or right arrow key. A
dialing menu can be accessed from the idle screen. Flip between idle screen and menu screen
by pressing the MENU or up arrow key.

LED STATUS SCREEN
Either in idle state or data state, there is an LED status screen

that can be accessed and displayed by pressing the left or right
arrow key at the menu's top level. This LED status screen has
five status indicators - DCD, DSR, CTS, RTS, and SQ. These status
indicators are identical to the LED indicators of the non-LCD
modems. Some of the status indicators are better expressed by
other screen displays, e.g., a data state screen means DCD is on,
and an idle screen means DCD is off; SQ is better explained by
S/N ratio and other impairment readings.

ARROW ON THE SCREEN
In some menu screens, you will see double left arrows (<<) or

double right arrows (>>). This means there are more items on the
left or right. Use the left or right arrow key to select them. If
you can only see a double right arrow, this indicates that the
current item is the first item of the menu. By pressing the left
arrow key, the screen will wrap over to the last item. On the
other hand, if you only find a double left arrow displayed, this
indicates that your current item is the last item in that menu.
Similarly, pressing right arrow key at this point will cause the
screen to wrap around to the first item.

DIALING
From the IDLE SCREEN (1) of Fig. 4-1 you can use the right or

left arrow key to scroll through D, R, O, and A. Move the
blinking cursor to "D", press ENTER, and you will go into the
Dialing Directory.

Valid digits/characters for dialing are:
0 1 2 3 4 5 6 7 8 9 * #

, Pause

; Return to COMMAND STATE
@ 5 second silent wait
! Hook flash
P Pulse dialing
R Reverse dialing
T Tone dialing
W Wait for dial tone

- Digit separator
<bs> backspace

DIAL MEMORY
The first menu of the Dialing Directory is DIAL MEMORY. Pressing

the ENTER key will show the following screen:
((MODE-10 (mod.)))

Equivalent AT commands:
AT&Z? View all stored phone numbers.

ATDSn n=0-9, dial stored number.
The first stored number shown on the menu is the default dial

number and can be selected from the DEFAULT DIAL menu. By
pressing the left or right arrow key, you can view up to ten
different numbers stored in memory. Pressing the ENTER key will
dial the selected number. The first line of the LCD can display
up to 16 characters, however, up to 25 characters can be entered.
Characters 17 through 25 are displayed on the second line of the
LCD display.

STORE NUMBER
Again, pressing the right arrow key from DIAL MEMORY will move

the menu to STORE NUMBER. Pressing the ENTER key at this point
will produce the following screen display:

((MODE-11 (mod.)))
Equivalent AT commands:
AT&Z? View all stored phone numbers.

AT&Zn=1234567 Store phone number to memory location 0-9.
Just like DIAL MEMORY, ten different numbers can be viewed and

selected. If you want to add a number to memory, select an unused
memory location and press ENTER. The blinking cursor will change
into an underscore and will move to the next right position of
the colon(:). SELECT MEMORY will change to SELECT DIGIT. Press
the left and right arrow keys to scroll through the valid digits
and characters for dialing. Pressing ENTER will confirm the
selected digit and cause the cursor to move to the next position.

Repeat the above procedure to finish entering the number, then

press ENTER again to save the entry in the EEPROM. The stored
numbers will remain in memory until you revise or delete them.
Pressing the up arrow key in the process will abort and exit the
current number entry and nothing will be changed or saved.

DIAL NUMBER
The same procedure is used when entering numbers, as in the STORE

NUMBER operation. After number entry is completed, press the
ENTER key to dial the number.

((MODE-12))
Equivalent AT command:
ATD1234567 Dial phone number.

MANUAL DIAL AND DATA/VOICE SWITCHING
Use of a telephone set to make a call, in which an answer tone

comes back, is normally called Manual Dial. Once the other side
answers, access the `O' (Originate) by using the left or right
arrow key so the blinking cursor settles on the `O'. Then press
the ENTER key to start the modem handshaking sequence.

Equivalent AT command:
ATD Originate on-line.
When dialing a person, use the telephone to make the call. When

someone on the other side answers, decide who will be the
Originate modem and who will be the Answer modem. Once an
agreement is reached, use the left or right arrow key to select
the `O' or `A' for Originate and Answer. Then press the ENTER key
to start the modem handshaking sequence.

Equivalent AT commands:
ATD Originate on-line.

ATA Answer on-line.
When you want to switch from modem to voice, simply lift up the

handsets of both sides and press the ENTER key while the blinking
cursor is on the `H' or Hang Up. The LCD display will show
"DISCONNECTING ?" to ask for a confirmation. Press ENTER again
and the modem will change from data to voice communication. When
both sides wish to return to data communication, one side should
press `O' while the other side presses `A' (as explained
previously). This operation will reinitiate the modem handshaking
and enable data communications.

For U-1496E, use the VOICE/DATA toggle switch for data/voice
switching and use the ANS/ORG switch to select originate mode or

answer mode on-line. Whenever your modem establishes a connection
with another modem, one of the modems must be in answer mode and
the other modem must be in originate mode or a connection is not
possible.

Equivalent AT commands:
+++ Escape sequence code; causes a modem to return to command

mode. Enter escape sequence in data state and wait for the modem
to respond.
ATH On-hook; disconnect the modem.
ATD Originate on-line.
ATA Answer on-line.

REPEAT LAST DIAL
Access `R' (Repeat last dial) by pressing the left or right arrow

key and the ENTER key. Before a connection is made, any key
pressed from the front panel or terminal keyboard will abort the
redial operation.

Equivalent AT commands:
ATDL Repeat last dial.

A/ Repeat last command once.
A> Repeat last command once, retry the last call up to 9
(depending on the country) times.

AUTO ANSWER
Move to the STATUS REGISTER menu, and change the S0 value to the

number of rings until the modem will automatically answer. A
value of zero disables auto answer.

Equivalent AT commands:
ATS0=0 Disable auto-answer.

ATS0=n Auto answer on n rings.

DIALING MESSAGE
Dialing from the terminal or front panel will cause the following

screen to be displayed on the LCD.
((MODE-13))
Dialed phone number will be displayed on the second line of the

20 X 2 LCD screen. If the number exceeds 20 digits, only the
first 20 digits/characters will be displayed. If the phone jack
is not plugged in or not attached, the LCD screen will display
the following:

((MODE-14))
then the modem will go back to the IDLE STATUS screen. If the

line is busy, after 3-5 seconds, the LCD displays:
((MODE-15))
then goes back to IDLE STATUS screen. If the phone company is

ringing the remote modem, a RINGING message is sent to the
terminal. Setting S42.6 = 1 will disable this "RINGING" result
code. If any key interrupt occurs (from the terminal or panel)
and breaks in before the connection is made, the screen displays:

((MODE-16))
then goes back to IDLE STATUS screen. If the time interval

depicted in the S7 register expires, and the line is still not
connected, the LCD screen shows:

((MODE-17))
then goes back to the IDLE STATUS screen. If the first

handshaking signal has been detected, the LCD screen will
display:

((MODE-18))
If a connection has been made, the LCD will display the actual

connected status. These are data state screens.
((MODE-19 (mod.)))
The ON-LINE STATUS screen 1 shown above means:
Link Option V.32bis

Line Speed 14400 bps
Error Control V.42 (implied by V.42bis)
Data Compression V.42bis
Line Type Dial-up
Data Format Asynchronous
Instant Transmission Throughput 25820 bps (BLANK if
synchronous mode was connected) Instant Receiving Throughput
21324 bps (Link speed displayed if synchronous mode was
connected)

The ON-LINE STATUS screen 2 shows:
Signal to Noise ratio 26.7 dB

Receiving Signal level -25.1 dBm
Phase Jitter in received signal 0.4 degree
Frequency Offset in received signal - 0.6 Hz

The ON-LINE STATUS screen 3 shows:

Retrain Granted 0
Retrain requested 0
Round trip Echo Delay 128 T (1/2400 sec)
Carrier Loss counts 0

The ON-LINE STATUS screen 4 shows:
FRN (Fast Rate reNegotiation) Granted 0

FRN Requested 0
Blocks Retransmitted 0
FCS (Frame CheckSum) Errors 0

Pressing the left or right arrow key in any one of the ON-LINE
STATUS screens will cause the LCD to scroll through the three
screens. We will discuss the ON-LINE STATUS screen 2, 3, and 4 in
more detail in Chapter 17 Diagnostics.

Pressing the ENTER key while in any ON-LINE STATUS screen will
cause the LCD to display the following:

((MODE-20))
Equivalent AT commands:
+++ Escape sequence code, causes the modem to return to command

mode. Enter escape sequence in the data state and wait for the
modem to respond.
ATH Go on-hook; disconnect the modem.

Pressing up or selecting `NO' will switch the screen back to the
ON-LINE STATUS screen 1 and the modem remains on-line. Pressing
ENTER will hang up the line and cause the screen to revert to the
IDLE STATUS screen, awaiting for your next command.

Pressing up in either screen will change your current environment
to the CONFIGURATION menu. This will be discussed in the
succeeding chapter.

PANEL LOCK
The panel keyboard can be locked to prevent inadvertent changes

in modem settings. This is done by setting the S-Register S28 bit
1 value to 1 or using the PANEL LOCK menu from the panel, or by
issuing the AT*L1 command from the terminal. Issuing the AT*L0
command will return the key operation to normal. Alternatively,
pressing the left and right arrow keys simultaneously will unlock
the panel. In locked panel mode, the ENTER key will lose effect
in changing or saving settings; panel command execution is also
disabled. However, viewing in the panel is not affected.

Chapter Five - MODEM PARAMETER SETTINGS

This chapter explains how to view and set various major modem

parameters using the U-1496 CONFIGURATION menu tree. U-1496E,
U-1496P, and U-1496B users can also consult this menu tree for
available parameter options, but use the equivalent AT command to
set the parameter.

Here we define the various levels of the CONFIGURATION menu tree
as:

CONFIGURATION menu
submenus
parameter menus
parameter selection

where CONFIGURATION menu is the root of this menu tree. Some
submenus, like STATUS REGISTER, SAVE TO, and RESET, have a direct
parameter selection under them and do not have the parameter menu
level.

Under the CONFIGURATION menu, there are seven submenus (see also
Fig. 4-1):
TERMINAL OPTIONS
MODEM OPTIONS
ERROR CONTROL
AUDIO OPTIONS
STATUS REGISTER
SAVE TO
RESET

Every submenu screen defines certain parameters of U-1496
operation. Submenu selections are made by using the left and
right arrow panel keys. Pressing the ENTER key will access the
parameter menu and pressing the up arrow key will return you to
the CONFIGURATION menu.

PARAMETER MENU
The parameter menu selections are made by using the left and

right arrow keys to move from one to the other. Pressing the up
arrow key will return you to the submenu screen. Press ENTER to
go into Parameter Selection. You will notice that a blinking
cursor will appear at the left side of the `=' sign.

PARAMETER SELECTION
Press the left or right arrow key to view and scroll the

available parameters. Only the parameter currently in effect will
have the `=' sign before their respective selections, otherwise a
`:' sign will appear, meaning that this current parameter is a
selectable option. By pressing up to quit from the viewing, the
screen will return to parameter menu and the parameter will
remain unchanged. Press ENTER to make the selected parameter
active.

To save the current parameter settings to non-volatile EEPROM,
access the SAVE TO submenu in the CONFIGURATION menu and select
from the various profiles you wish to save the changes to, and
the parameter settings will be permanent in that profile. You can
always recall in these settings by resetting from that profile.
Access RESET and choose `=FACTORY DEFAULT' and the active
parameter settings will revert to original factory defaults.
Also, S-Register's content can be individually modified in the
STATUS REGISTER sub menu.

REGISTER'S CONTENT MODIFICATION (STATUS REGISTER)
When you access the STATUS REGISTER submenu in the CONFIGURATION

menu, the blinking cursor will be changed into an underscore `_'
and the content will be blanked out. Press the left or right
arrow key to scroll through a series of hex digits, then press
ENTER when the desired digit appears. Remember that both digits
must be entered. Pressing up will quit the entry procedure, the
blinking cursor will reappear, and the content will remain
unchanged.

MENU TREE ELEMENTS
For the rest of this chapter, we will explain the parameter

selections of each parameter menu and of each configuration
submenu. The large boldface title of each section is the name of
each configuration submenu under which each boldface subtitle is
the name of each parameter menu. Under each parameter menu, there
are a list of parameter items. These are the selectable parameter
items in this parameter menu. On the right of each parameter item
is the equivalent AT command to select or set this parameter.
After that is a brief explanation of this parameter. A `+' sign
in front of a parameter item means that it is the default
parameter setting.

TERMINAL OPTIONS
DATA FORMAT
+ ASYNC AT&M0 Operate as an asynchronous modem with

data buffering, may work with data compression and/or error
control. Fixed DTE speed with flow control.
SYNC DATA AT&M1 Modem accepts asynchronous command, but
changes to synchronous data mode and exchanges data synchronously
with remote modem.
DIRECT AT&M2 Direct asynchronous mode without data
buffering. DTE speed equals link speed.
SYNC AT&M3 Modem accepts synchronous command (V.25bis)
and exchanges data synchronously with a remote modem. You can
also dial from the front panel or use a telephone set to make a

connection.
CHARACTER LENGTH
+ 10 AT*C0 10-bit characters.

11 AT*C1 11-bit characters.
9 AT*C2 9-bit characters.
8 AT*C3 8-bit characters.

The character length includes start bit, data bits, parity, and
stop bit(s).

COMMAND SET
+ AT AT*I0 Modem accepts asynchronous AT commands.

V.25bis AT*I1 Modem accepts asynchronous or
bit-oriented synchronous V.25bis commands.
DUMP AT*I2 No command accepted. Modem ignores DTE data
in idle state.

Note: Only asynchronous V.25bis available on U-1496B.
DTE RATE
+ FIXED AT&B1 Modem serial port speed is always fixed

no matter what link rate (modem speed) is connected. If S44.6=1
and a non-ARQ connection is made, DTE rate follows link rate as
if &B0 is set.
FOLLOWS LINK RATE AT&B0 Modem serial port speed is set
in accordance with the link rate. If S44.6=1, the DTE speed is
fixed at 19200 bps when the link speed is above 9600, and at 9600
when the link speed is 7200, and at link speed when it is below.

Note: If you wish to keep your DTE rate fixed, you should choose
a buffered transfer. (see DATA FORMAT)

DTR OPTIONS
IGNORED AT&D0 Modem assumes DTR always ON, ignores the

changes.

108.1 AT&D1 An OFF-ON DTR transition causes the
modem to dial the number specified under the DEFAULT DIAL of the
MODEM OPTIONS submenu. An ON-OFF transition disconnects the modem
from the line.
+ DTR/108.2 AT&D2 Data Terminal Ready, an ON-OFF
transition of DTR will disconnect modem from line.

108.2 + RST AT&D3 Same as &D2 but DTR OFF also causes
reset from profile 0.

Note: Not all computers provide a DTR signal at their serial port connector. If such situations
arise you must use the IGNORED setting (AT&D0).

DCD OPTIONS

+ TRACKS CARRIER AT&C1 DCD ON when carrier is detected.
(see also S38b3). If S42.7=1, DCD only pulses off for 0.5 sec
when carrier loss happens.
ALWAYS ON AT&C0 Modem forces DCD always ON.

RTS OPTIONS
+ IGNORED AT&R1 Modem assumes RTS always ON, ignores the

changes.
CTS TRACKS RTS AT&R0 Delay before CTS responds to RTS's
change. The delay is set in S26.

Note: Effective only on synchronous mode. This setting is ignored
in asynchronous mode. RTS is always used as hardware flow control
in this case.

DSR OPTIONS
+ ALWAYS ON AT&S0 Modem forces DSR always ON.

DATA SET READY AT&S1 According to CCITT. DSR ON during
handshake. If S41.5=1, DSR follows DCD, pulses off for 0.5 sec
for DCD on-off transition. If S44.4=1, DSR follows DTR.

COMMAND ECHO
+ ENABLED ATE1 Modem echoes commands.

DISABLED ATEO Modem does not echo commands.

RESULT CODE
+ ENABLED ATQ0 Modem returns result code.

DISABLED ATQ1 Modem does not return result code.
ATQ2 If S40.1=1, modem does not return result code in
answer mode.

DTE ASYNC SPEED
76800 Select DTE port asynchronous serial speed.

57600 AT command auto speed detection will override
this selection.
38400
19200
16800
14400
12000
9600
7200
4800
3600
2400
1800