SIM800A not connecting with Airtel SIM Card

Hello sir, i am using SIM 800A module with arduino uno. it operates and send sms properly with vodafone, Bsnl, and idea simcard but not with Airtel.
with Airtel it send a blank sms.please suggest me the solution.

@Ganesh
Please post your query with new thread under correct category.

This problem is strange. SIM card is not a matter of sending blank SMS. It should work fine with Airtel SIM as working with other SIM card.

Do you using MCU to send SMS? If yes, Keep MCU aside and connect your GSM module to PC serial and try sending SMS using any serial terminal with AT commands.

1 Like

hello sir see the code i am using,

#include <SoftwareSerial.h>
SoftwareSerial gsm(2, 3 );

char phone_no[] = “8007032136”;

void setup() {
Serial.begin(9600);
gsm.begin(9600);
}

void loop()
{
delay(300);

Serial.println(“AT+CMGF=1”);
gsm.println(“AT+CMGF=1”);
delay(2000);
Serial.print(“AT+CMGS=”");
gsm.print(“AT+CMGS=”");
Serial.print(phone_no);
gsm.print(phone_no);
Serial.write(0x22);
gsm.write(0x22);
Serial.write(0x0D);
gsm.write(0x0D);// hex equivalent of Carraige return
Serial.write(0x0A);
gsm.write(0x0A);// hex equivalent of newline
delay(2000);
Serial.print(“Message from GSM”);
gsm.print(“Message from GSM”);
delay(500);
Serial.println (char(26));//the ASCII code of the ctrl+z is 26
gsm.println (char(26));

}

and this is the GSM module I used.

What is the difference between Serial.begin(9600); and gsm.begin(9600); ?