Sending AT Commands to a mobile phone (Ericsson)

Posted on 2002-06-04
Last Modified: 2010-05-02
Hi everyone,
I'm trying to send AT Commands to an Ericsson T39 phone using the RS-232 Data Cable, but I have no idea how to set this up in VB...I added a Comm object and I am sending the command using the .Output = [Value] method but the phone isn't responding to any command and isn't returning anything...
Question by:raybeam
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Accepted Solution

mcoop earned 100 total points
ID: 7054995
Probably the best way to work, is to make sure your physical connection is valid, and that the phone is willing to talk.

Use Hyperterminal or similar to open he port to the phone, then manually test the commands you are trying to use - then you can see if the phone is reacting as expected etc.

Once you know what beast you are fighting, you can then plan a coded attack using what you learned in Hyperterminal.

Of course there are better tools than HT - but you already have it and it's free.


Author Comment

ID: 7055003
I tried's giving me funny characters, I tried changing the baud rate, parity bits, and stuff but it's still giving me funny characters...eventhough Ericsson said that you should use a "9600,n,8,1" setting...
LVL 11

Expert Comment

ID: 7055061
maybe this is not what you want to hear, but dont you have any manual or reference card for that phone, regarding its rs232 posibilities?

try the same you are doing with an external modem (or internal, i prefer externals), if you code works fine with your modem, then it should do the same with your t39, probably your t39 settings are not right. (speed, parity,stop bits, etc)

i have no experience whatsoever in irda or bluetooth, but if you are already connected things should be very straight.

if you use IRDA then make sure you are using the right version/driver/etc.

here are some Delphi sources that will probably give you an idea.

some more info here.
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LVL 11

Expert Comment

ID: 7055071
also if you have any other serial device (modem or printer) try changing them to another port
if you are using port 1 try for port 3 to be free, if you are using port 2 then try to get the port 4 free.

this is about that irq sharing(conflicts)  the com ports used to do (i dont know if they still do), but it allways gave problems like moving your serial mouse and "hearing" it in your modem speakers or so.

also turn off then on your computer and make sure you where not using that port for something else (it wont work if you disconnect a mouse and then attach other device, you should start with that as a free port)

take a look at your bios setup screens, maybe the port is even disabled or disconnected from the inside of your PC case.

IF YOU CAN ATTACH SOME OTHER DEVICE AND MAKE YOUR TESTS THERE then you will be able to isolate the problem to the t39 configuration.

Expert Comment

ID: 7055559
I don't have a T39 - but I assume that it has an internal modem ???  Otherwise you need to use Ericsson's data package that manages the phone connection (in binary - hence odd characters)

In the latter case, your AT commands are processed by the software, and only then sent to the phone in their proprietary format.   The existence of an RS232 link does not guarantee the protocol will be ASCII or human readable.

good luck

Author Comment

ID: 7056096
The list of commands is with me, but I am receiving funny language using the default setting which is (9600,n,8,1)

I'll have to investigate this further...

Author Comment

ID: 7063296
Thanx mate, never knew Hyperterminal can be used for 2-ways communicaton...

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