GSM Modem not sending any reply to PIC

#include "LCD.h"
#define NULL 0

void SendMessage(char*);
void EnableUART (void);
void DisableUART(void);
void CHEK_isr	(void);
void TX_isr		(void);
void RC_isr		(void);

const char MODEM_SEND[] = "AT\n\r";
static char MODEM_RECV[10];
void main()
{
	signed char cIndex = 1;
	unsigned char  ucResponse[2];
	
	InitialiseDisplay();
	EnableUART();

	while(1)
	{
	}

}

void EnableUART ( void   )
{
	
		TRISCbits.TRISC6   	= 1;	//TX PIN
		TRISCbits.TRISC7   	= 1;	//RX PIN

		SPBRG 			   	= 25;	//BR = 9600
		TXSTAbits.TXEN 	   	= 0;   
		TXSTAbits.BRGH 	   	= 1;
		RCSTAbits.SPEN 	   	= 1;
		RCSTAbits.CREN 	   	= 1;
		BAUDCTLbits.BRG16  	= 0;		
		TXSTAbits.SYNC 	   	= 0;		
		TXSTAbits.TX9  	   	= 0;
		TXSTAbits.TXEN 	   	= 1;

		INTCONbits.PEIE		= 1;    //Enable Peripheral intr 
		PIE1bits.RCIE	 	= 1;	//Enable RX intr
		PIE1bits.TXIE	 	= 1;	//Enable TX intr
		IPR1bits.TXIP		= 0;	//TX - Low Priority intr
		IPR1bits.RCIP		= 0;	//RX - Low Priority intr
		RCONbits.IPEN 		= 1;	//Enable Interrupt Priorities
		INTCONbits.GIEL	   	= 1;	//Enable Low Priority Intr
		INTCONbits.GIE 	   	= 1; 	//Enable interrupts
		
}

void SendMessage( char* Msg)
{

		int len, count = 0;
		TXSTAbits.TXEN 	   = 1;	//Enable UART	  

		while( *(Msg+count) != NULL )
		{
			TXREG = ( *(Msg+count) );    			
			while( !PIR1bits.TXIF )
			{
			 	//Wait till TXREG become empty
			}
			Delay(1);
			count++;
		}	

	TXSTAbits.TXEN = 0;

}

void DisableUART( void   )
{
	TXSTAbits.TXEN = 0;
}

#pragma code low_vector = 0x18
void low_ISR (void)
{
_asm goto CHEK_isr _endasm
}
#pragma code

#pragma interruptlow CHEK_isr

void CHEK_isr(void)
{
	if( PIR1bits.TXIF == 1 )
	{
		TX_isr();
	}
	
	if( PIR1bits.RCIF == 1 )
	{
		RC_isr();
	}

}

void TX_isr(void)
{
	SendMessage(MODEM_SEND);
	TRISB = 0x00;
	PORTB = 0x0A;

}

void RC_isr(void)
{
	TRISB = 0x00;
	PORTB = 0x05;
	MODEM_RECV[0] = RCREG;
	WriteDataToDisplay(MODEM_RECV[0]);
}