microcontroller and gprs module interface problem

#include "DS89C4XX.h"
#include "stdio.h"

void main()
{

	char c;
 	char aa[40];
	int i=0;
/**********Serial port initialization**************************/
    SCON0  = 0x50;		        /* SCON: mode 1, 8-bit UART, enable rcvr      */
    TMOD |= 0x20;               /* TMOD: timer 1, mode 2, 8-bit reload        */
    TH1   = 252;                /* TH1:  reload value for 14400 baud @ 22.1184MHz   */
    TR1   = 1;                  /* TR1:  timer 1 run                          */
    TI_0    = 1;                  /* TI:   set TI to send first char of UART    */

/************End of serial port initialization****************/
			
	P1 = 0x0F;                   //to see if the LEDs blink conencted to P1 port
	msdelay(20000);
	P1 = 0xF0;                  //to see if the LEDs blink conencted to P1 port
	msdelay(20000);
/*Printing string in LCD before sending command to GPRS module*/
                printchar(0,0, "Sending AT command");

/*Sending AT command using serial port*/
	printf("AT\n");

/*Waiting for the response*/
	scanf("%s", &aa);

/*There is a LCD to show the result. I deleted the LCD codes for simplicity
   The LCD was showing outptu when conencted to PC terminal.
But it was not showing the output when conencted to GPRS module.*/
                printchar(0,0, aa);
	while(1);
}

import MDM
import MOD

ip='IP'
apn = 'internet'
server = '0.0.0.0'
MDM.send('AT+CGDCONT=1,'+ip+','+apn+','+server+'\r',0)
res = MDM.receive(20)
print res
username = 'whatever'
password = 'whatever'
MDM.send('AT#USERID='+username+'\r',0)
res = MDM.receive(20)
print res
MDM.send('AT#PASSW='+password+'\r',0)
res = MDM.receive(20)
print res


MDM.send("AT#GPRS=1\r",0)
res = MDM.receive(80)
print res

MDM.send('AT$GPSACP\r',0)
gps = 'This is GPS data:'+MDM.receive(30)
gps = gps.replace(' ','')
gps = gps.replace('\r','') # This is to remove unwanted characters
gps = gps.replace('\n','') # from the gps output.
gps = gps.replace('OK','')
print gps

web = 'www.e-secretary.net'
MDM.send('AT#SKTD=0,80,'+web+'\r',0)
res = MDM.receive(50)
print res

req1 = 'GET /gps/dgl.php?name='+gps+' HTTP/1.0'
req2 = 'Host: '+web
req3 = 'Connection: keep-alive'
MDM.send(req1,0)
MDM.sendbyte(0x0d,0)
MDM.sendbyte(0x0a,0)
res = MDM.receive(10)
MDM.send(req2,0)
MDM.sendbyte(0x0d,0)
MDM.sendbyte(0x0a,0)
res = MDM.receive(10)
MDM.send(req3,0)
MDM.sendbyte(0x0d,0)
MDM.sendbyte(0x0a,0)
MDM.sendbyte(0x0d,0)
MDM.sendbyte(0x0a,0)
res = MDM.receive(100)
print res