Sim 800 GSM Module not responding with Software Serial Library

HI !

I am trying to use SIm 800 GSM Module with Arduino UNO.

ARDUINO DIGITAL PIN 9 is connected to TX of GSM Module
ARDUINO DIGITAL PIN 10 is connected to RX of GSM Module

ARDUINO is powered by PC USB
GSM MODULE is powered by 12v DC Adapter.

I have tried the following code for making outgoing call: -

    #include <SoftwareSerial.h>
    SoftwareSerial mySerial(9, 10); // RX, TX of Arduino Uno
    void setup()
    {
      mySerial.begin(9600);   // Setting the baud rate of GSM Module  
      Serial.begin(9600);    // Setting the baud rate of Serial Monitor (Arduino)
      delay(10000); //wait for 10 seconds
      mySerial.println("ATD9464XXXXXX;" ); //dialing my mobile number
      Serial.println("Calling"); // printing message on serial monitor
      delay(10000); // wait for 10 seconds
      mySerial.println("ATH" ); // hang up the call
      Serial.println("END"); // printing message on serial monitor
    }
    void loop(){}
    //code ends here

this code is not working.

But if I directly connect GSM Module TX, RX to RX, TX of ARDUINO and the use the following code, it makes outgoing call and hangs up simply : -

    void setup()
    {
      Serial.begin(9600); //setting baud rate of serial communication with GSM Modem
      delay(10000); //wait for 10 seconds
      Serial.println("ATD9464XXXXXX;" );  // dialing mobile number
      delay(10000); // wait for 10 seconds
      Serial.println("ATH" );  // hang up the call
    }
    void loop() {}
	 //code ends here

Same issue is with sending / Receiving SMS also.

Can somebody guide me what is wrong with SoftwareSerial Library here in my code ?