GSM SIM900 Module working with Putty and not with Arduino Serial Communication

I am using a GSM SIM900 Module in my project,
I was able to make calls and send SMS through it using Arduino
and now its not able to do so.
I have checked the connections and the code.
They are the same as they were during its working state.

and now i tried interfacing GSM Sim 900 using RS232 and Putty and i am able to make calls through it buy unable to do the same using Arduino

void setup() {
// put your setup code here, to run once:

void loop() {
// put your main code here, to run repeatedly:

Clueless what to do
Please help.

What the heck is Serial.println("ATD9619261911;\r\n"); ?

And where we're the three plus signs that enable the AT&T mode? We're you not doing the +++ in putty?

While using Putty with the SIM 900 GSM Module, I had connected it to my laptop via a RS232 to USB converter. I need not put +++ commands for AT & T mode, I connected to the port my GSM was connected to and tested it first with command ‘AT’ and the reply was ‘OK’ then followed by ‘ATD**********;’. A call was successfully made to my phone. But when I am trying it via an Arduino Uno/Nano, it is not working. Tried the above code as well as a few others, all worked and I could make a call with the GSM module using Arduino but at present it is not working.

Screenshot (57).png

  1. How are you connecting the rs232 to arduino?
  2. Why is there no AT before ATD in arduino code?