As an owner of an AT&T Model 2224CEO error correcting modem, I have
experienced more than my fair share of problems trying to get the modem
to successfully work with various bulletin boards, Compuserve, Prodigy,
and UNIX(R) systems. I believe this modem to be superior to anything out
on the market for its price, but it takes a 4-year degree and multiple
changes to get it to interface with the aforementioned services. The
following information summarizes my trials over the past two years; all
interfaces to the services are via "Procomm Plus".

The 2224CEO modem supports the AT&T command mode (a user-friendly text
mode that is difficult to use with communication software packages but
much easier than HAYES commands when used in an interactive mode) and
the HAYES command set mode. Where applicable, both methods will be detailed.
The modem can be changed to use one set vrs. the other under a prescribed
set of conditions:

1) set the front panel S1 switches to all DOWN except Switch 5 (set SW 5
to UP). This switch is accessible by raising the sliding cover (located
to the left of the volume control).

2) push the RESET button (located left of the S1 switches).

3) turn on your PC, and run your communications software (with baud rate
set to 300, 1200, or 2400 baud).

4) depress the <ENTER> key until the a message similar to the following
one appears:

AT&T model 2224C
2400 bps

Dial, enter command, or h for help
:

the ":" is the default command prompt.

5) type the following lines, one at a time, followed by enter:

o12=y
o33=y
o34=1

This sets option 12 (transparent data mode) to yes (required to ensure file
download successes), option 33 to yes (required to change back and forth
between the AT&T command set and the HAYES command set), and option 34 to 1
(Direct modem mode, no error correction).

The modem is now ready to use, dependent upon what service is to be accessed.
When in the AT&T command mode, with option 33=yes, you can change to the HAYES
command set by typing "&&H" (followed by <ENTER>) from the ":" command prompt
(allow 5-7 seconds for reset and self-test); when in the HAYES command mode,
you can change to the AT&T command mode by entering "AT&&A" followed by <ENTER>
(again, allow 5-7 seconds for reset and self-test).

The error correction mode may be entered in the AT&T command set by changing
option 34 to either 2 (forced MNP error correction) or 3 (auto-error correction
detect); option 3 is recommended. Earlier modems (mid-1989 and earlier?)
support MNP Level 1-4 error correction protocol; I have had problems
downloading files when an AT&T 2224CEO modem is not on the other end.
Newer ones support MNP Levels 1-5; I can download files from RBBS of Chicago
with these modems, but NOT from Compuserve. For the most part, I recommend
setting error correction to OFF (o34=1 or AT\N1) before dialing if file
downloads will be attempted.

My recommendations for various services:

*** PRODIGY(tm) Electronic Service ***

This service REQUIRES a HAYES compatible
modem. In your PRODIGY directory, there is a configuration file (whose
name I don't remember since I dropped this service) which contains the
following two lines:

bps:24;          (or "bps:12;" for 1200 baud use)
port:1;          (or "port:2;" if COM2 is used)

Add the following line to use the AT&T 2224CEO modem:

modem command:AT&F\A0%A0\C0\E0\G0\J0\N0\Q0\T90$;

*** Compuserve(tm) Information Service ***

For HAYES command mode, I use the following Procomm Plus initialization
command:

ATE1 S7=255 S11=55 V1 X1 S0=0^M

Note that the "^M" (Ctrl-M) should be replaced by <ENTER> if the command
is typed in an interactive manner. Error correction should be OFF (AT\N1).

For AT&T command mode, all options default except o12=y, o33=y, o34=1.

*** RBBS of Chicago ***

For HAYES command mode, this is the same as Compuserve with the exception
that you may try to use error correction (AT\N3); I use "1K-Xmodem"
download protocol on RBBS of Chicago with "Ymodem" on Procomm Plus.

For the AT&T command mode, same as Compuserve except you may try to
use error correction (o34=3).

I hope the above information will spare you the grief I've endured. This
modem is a better buy than HAYES modems if you're willing to work a bit,
and it comes with a two-year warranty. I'll confess that I work for AT&T,
and this modem works much better than others in the market when I dial
into my 3B2 UNIX(R) computer at work. Once it is configured properly,
I have not had any problems with noise or downloading which can't be
attributed to my own errors.

Bill Sugas
