Dialing modem

Evgeni57

Hi, I'm trying to dial phone number and using SerialPort control for this, which is initialized with my USB modem.

SerialPort serialPort1 = new SerialPort("COM5", 115200, Parity.None, 8, StopBits.One);
serialPort1.Open();
serialPort1.Write("ATDmyphone\r");
serialPort1.Write("ATH\r");
serialPort1.Close();

everything works except 1 thing - there is no sound from the modem. I tried to use ATM2 and ATL3 commands before I start to dial - but there was still no sound. But when I create dial-up network connection, and dial from its dialer - there is a sound. What am I missing here? thanks!

T M Gray

Are you sure it isn't just dialing pulse? That can be harder to hear than tone. You should use ATDT just to make sure.

Evgeni57

I used ATDT as well - no sound :(

Luc Pattyn

I don't know, however I would insert a big delay (3 seconds as a first experiment) between every pair of statements, so the system can settle before your program continues; as it is now, it is all done in a few milliseconds, maybe something isn't fast enough to keep up. If that helps, you then can reduce the delays until it starts to fail again. :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles] Nil Volentibus Arduum

Please use <PRE> tags for code snippets, they preserve indentation, and improve readability.

monstale

Hi, what does modem answer to each command? Bye

Evgeni57

this is the code:

   serialPort1.DataReceived += new SerialDataReceivedEventHandler(serialPort1\_DataReceiver);
        serialPort1.Open();
        string answer;
        serialPort1.Write("ATM2\\r");
        answer = serialPort1.ReadLine();          //answer = "\\r"
        serialPort1.Write("ATL3\\r");
        answer = serialPort1.ReadLine();          //answer = "OK\\r"
        serialPort1.Write("ATDT" + phone + "\\r");
        answer = serialPort1.ReadLine();          //answer = "\\r"
        serialPort1.Write("ATH\\r");
        answer = serialPort1.ReadLine();          //answer = "OK\\r"
        serialPort1.Close();

'answer's' value are commented. thanks.

Evgeni57

tried to put 3 seconds sleep between each command, but it still dials withut the sound.

monstale

Hi, please try ATM1\r instead of ATM2 bye

Evgeni57

I tried, but there is still now voice :(

Rajesh Anuhya

try this below

serialPort1.Write("ATDmyphone;\r");

put ";" after your phone number

Rajesh B --> A Poor Workman Blames His Tools <--

Evgeni57

AFAIK, ';' tells the modem to return to return to command mode after the phone was dialed. How this may help? I tried it, but still there is no sound :( Thanks for your advice.

Rajesh Anuhya

Then.., that is very difficult to solve your problem by us, you have to debug the dialer software that which "AT" commands are sending to the modem, Use a Serial Port Monitor to see the AT commands are sending by the dialer software.., download the serial monitor from the following link http://www.hhdsoftware.com/products/[^] Thanks & Regards

Rajesh B --> A Poor Workman Blames His Tools <--

Chuck Richards

Did you ever resolve this? What modem type are you using?