Navas 28800-56K Modem FAQTM
(Answers to Frequently Asked Questions)
H. BRAND-SPECIFIC INFORMATION
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Email comments and suggestions to John Navas
Any other 3Com/USRobotics tips?
Warning: 3Com/USR has indiscriminately slapped the "Sportster" name
on so many different products that the author no longer feels it is a reliable
product guide. For example, recent "Sportster 28800" and "Sportster 33600"
modems have considerably different S-register settings as compared to the
original "Sportster 28800" product. This invalidates a good deal of
advice, including some of the material in this FAQ.
Certain 28800 Sportster models can be inexpensively upgraded
to 33600 (including Selective Reject).
Supervisory Update Information" (Note: the dates in the firmware
table are not necessarily the dates of the latest versions.)
Useful modem commands:
ATI6, issued after a disconnect,
will tell you the reason for the disconnect. Disconnect reasons are explained
in the Courier manual.
ATI6 will tell you your current modem-to-modem connection speed
if you escape (e.g., with "+++") to command mode while online. With
split/asymmetric speeds (see What are split/asymmetric
speeds?), ATI6 will report the two speeds as receive/transmit.
(See also "Why can't I get back on-line
after I escape to command mode?" To display the current connection
speed when using Trumpet Winsock on a SLIP/PPP link, see "Any
Trumpet Winsock tips?")
ATO will return you to on-line mode after you escape to command
mode; ATO1 will also request a retrain
(which may help if line conditions have changed substantially).
ATI7 will tell you what firmware version (date) you have.
For a good description of the output of the ATI6 and ATI11
commands, see the FAQ by USR UK.
If you are running Windows 95/98, the output of all the ATIn commands
can be easily displayed with Modem Diagnostics. (See "Any
Windows 95/98 tips?")
If you experience problems connecting to certain V.34 modems:
It may help to disable the 3429 symbol rate (S54.5=1), which confuses
certain modems (e.g., Hayes) that are not fully V.34 compliant during
It may help to disable V.FC (S56.7=1).
It may help to disable V.42 detect phase (S27=48).
If you experience problems connecting to certain V.34/V.FC modems, or you
otherwise want to connect with V.FC when the remote modem supports both
V.34 and V.FC, disable V.8 (S54.7=1), which effectively disables
If you have a particular number where you sometimes connect at a very slow
speed but get a much higher speed when you immediately redial, find out
if there is a Hayes modem at the other end. If so, it may be possible to
correct the problem by updating the Hayes firmware.
If you experience problems connecting to certain older MNP modems (esp.
at 2400 bps), try S15=64. This option is only documented for the
Courier ("Unusual MNP-Incompatibility"), but may work for the Sportster
If you hear a strange ringing sound after dialing and before the remote
answers, that's Call Indicate. It's a good idea to disable it (S54.6=1),
because it can cause connection problems with certain modems.
Some users have reported that resetting the modem before each call improves
the chances of a good connection. To do this, use ATZn instead
of AT&Fn. The options for ATZn are:
Z - reset and load profile Yn
Z1 - reset and load profile 0
Z2 - reset and load profile 1
Z3 - reset and load &F0 defaults
Z4 - reset and load &F1 defaults
Z5 - reset and load &F2 defaults
In other words, ATZ4 is a good alternative to AT&F1.
Generally the only problem is that you can't put more commands on the same
line with ATZn as you can with AT&Fn; e.g.,
you can do AT&F1S11=55 but not ATZ4S11=55. If you
have a comm program that can issue more than one initialization string
(e.g., HyperACCESS for Windows or WinComm PRO), you can simply put
additional commands in a second command string; e.g., ATZ4 followed
If you experience faxing problems, in addition to the other suggestions
in this document (e.g., "What
about third-party comm drivers for Windows?" and "Any
other Windows tips?") you should make sure that you have firmware dated
4/18/95 or later. (For a firmware upgrade, call 3Com/USR at 847/982-5151.)
Otherwise, it might help to initialize the modem with S36=0. If
you are using Symantec WinFax, you might also try limiting your send and
receive speeds to 9600 bps by adding the following to the [General]
section of your WINFAX.INI file:
With the Sportster (not the Courier), watch out for which profile you have
set. If Y1 is set (which selects profile 1 rather than profile 0), and
you do (say) ATS11=55&W, and then later use ATZ to
initialize your modem, you won't get the S11 setting you
saved! The reason is that &W always saves to the profile 0,
while ATZ loads whatever profile Yn is set to, in this case profile
Options that are controlled by dipswitches are not saved
in NVRAM (profiles 0 and 1). If you want them to be in a known state without
worrying about the dipswitches, you should set them in your initialization
string (e.g., E1Q0V1S0=0&C1&D2 for the default
An official table of Sportster models and firmware versions is available
Supervisory Update Information".
To obtain an SRO (Service Request Order) number for modem repair
or upgrade, see "USRobotics on the Internet".
Where can I get information on my Rockwell-based
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