microcontroller - STM32F031K6 HAL UART Interrupts problem

I got a new STM32F0 31 K6 nucleo board and I need to make a GSM UART interface on that board. I need to send an AT and receive an OK from the GSM board as a first step.I am able to transmit AT successfully But cannot receive anything. I am using IAR. I am using PA9 - TX and PA10 - RX. How to create a transmit and receive code using interrupts using this HAL library. I wrote code using interrupts and it's not giving a single character. This is my code

     int main(void)
{

  HAL_Init();
  /* Configure the system clock to 48 MHz */
  SystemClock_Config();

    /* Configure LED3 */
  BSP_LED_Init(LED3);
  UART_Init();
  BSP_LED_Off(LED3);
  if(HAL_UART_Transmit(&UartHandle, (uint8_t*)aTxBuffer, TXBUFFERSIZE,100)!= HAL_OK)
  {
    Error_Handler();
  }

    if(HAL_UART_Receive_IT(&UartHandle, (uint8_t *)aRxBuffer,6) != HAL_OK)

  {
    Error_Handler();
  }
   /*##-5- Wait for the end of the transfer ###################################*/   
  while (UartReady != SET)
  {
  } 
    /* Reset transmission flag */
  UartReady = RESET;
  /*if(HAL_UART_Transmit(&UartHandle, (uint8_t*)aRxBuffer, 6,1000)!= HAL_OK)

  {
    Error_Handler();
  }*/
  while (1)
  {
  }
}

IRQ handler

void USARTx_IRQHandler(void)

{
  HAL_UART_IRQHandler(&UartHandle);
}

Receive callback function

void  HAL_UART_RxCpltCallback(UART_HandleTypeDef *UartHandle)
{
  if(UartHandle->Instance == USARTx)
  {  
    /* Set transmission flag: transfer complete */

    UartReady = SET;
    BSP_LED_On(LED3); 
  }
}

And when I am debugging the code stuck at this point .

/*##-5- Wait for the end of the transfer ###################################*/   
  while (UartReady != SET)
  {
  } 

My actual application is to send an SMS to the GSM board using UART and collect the reply in a buffer and then parse it.First i need to make this interface And I cannot use DMA as there is no idea on how much data is received on this commuunication.

please help guys..

Regards, olivia