node js AT command return +CMS ERROR: 302

Question

I'm trying to send sms using AT commands from huawei modem. but sometimes when using AT+CMGS it returns +CMS ERROR:302

This is my code

var SerialPort = require('serialport');
var port = new SerialPort("/dev/ttyUSB0", {
baudRate: 9600,
dataBits: 8,
parity: 'none'
});

console.log('port is now open');

port.on("open", function () {

console.log('Serial communication open');
port.write("AT");
port.write('\r');
port.on('data', function(data) {
    console.log("Received data: " + data);
});



gsm_message_sending(port, "test", "+94758034032"); 
 });

function gsm_message_sending(serial, message ,phone_no) {
serial.write("AT+CMGF=1");
serial.write('\r');
serial.write("AT+CMGS=\"" + phone_no + "\"");
serial.write('\r');
serial.write(message); 
serial.write(Buffer([0x1A]));
serial.write('^z');
}

i need help to figure out what causes this error.. thanks