Interrupt not working(tx in softuart)(reception is inbuilt uart in the interrupt mode)

#include<softuart.h>
#include<stdio.h>
#include<reg51.h>

void uart_init();
sbit sw=P1^7;

unsigned char rx();
code unsigned char rd[] = "AT+CMGR=1";
code unsigned char ne[] = "AT+CNMI=2,2,0,0,0";
unsigned int r=0,m=0,s1=0,n1=0,f1=0,m2=0;
unsigned char gs,mes_dat[]=0,mess[]=0;
extern void lcd_init();
void lcd_cmd(unsigned char);
void lcd_data(unsigned char);
//void wait();

void gsm_delay(unsigned int);
unsigned char txt[]="AT+CMGF=1";
unsigned char no[] ="AT+CMGS=\"9940151239\"";
unsigned char del[]="AT+CMGDA=\"DEL ALL\"";

unsigned char sen[]="SENSOR";

void send_no();
void new_mess();
void gsm_read();

void delete();
void gsm_read();
void mode();
unsigned char rx();
unsigned char w, re,rx_data;
void tx(unsigned char);

void serial(void) interrupt 4
{

if(TI==1) { TI=0; SBUF = '\0'; //ES=0; } else if(RI==1) { rx_data = SBUF;

if(rx_data=='+') { do { mess[m2] = rx_data;

m2++; RI=0; }while(rx_data=='T'); }

RI = 0; }
}

void main()
{ uart_init(); lcd_init(); mode(); new_mess();

// delete();

while(1) { IE = 0x90; m = 0; r = 0; s1 = 0; m2 = 0;

re = rx_data;

if(re=='+') { RI = 0;

if(SBUF=='C') { lcd_data('1'); RI = 0; if(re=='M') { RI=0; lcd_data('2'); if(re=='T') { RI=0; do { gs = re; RI = 0; }while(gs!=0x0a);

do { gs = re; RI = 0; }while(gs!=0x0a);

m=-1; do { m = m+1;

mes_dat[m] = re; RI = 0;

}while(mes_dat[m]!=0x0d); mes_dat[m] = '\0'; m=0; lcd_cmd(0x01); lcd_cmd(0x80); while(mes_dat[m]!='\0') { lcd_data(mes_dat[m]); m++; } } } } } while(sw==1); m2=0; while(mess[m2]!='T') { //lcd_data(mess[m2]); tx(mess[m2]); m2++; }

send_no();

while(sen[s1]!='\0') { putc(sen[s1]); s1++; } putc(0x1a);

lcd_data('L');

gsm_delay(1000); gsm_delay(1000); gsm_delay(1000);

}

}

void new_mess()
{ n1=0; while(ne[n1]!='\0') { putc(ne[n1]); n1++; } putc(0x0a); putc(0x0d); gsm_delay(1000);
}

void mode()
{ f1 = 0; while(txt[f1]!='\0') { putc(txt[f1]); f1++; }

putc(0x0a); putc(0x0d); gsm_delay(1000);
}

void uart_init()
{ TMOD = 0x20; TH1 = -3; SCON = 0x50; TR1 = 1; //IE = 0x90;
}

/*unsigned char rx()
{ unsigned char rec; while(RI==0); rec = SBUF; RI = 0; return rec;
}

void delete()
{ unsigned int d ; d=0; while(del[d]!='\0') { putc(del[d]); d++; } putc(0x0a); putc(0x0d); gsm_delay(1000);

} */

void send_no()
{ unsigned int s=0; while(no[s]!='\0') { putc(no[s]);

s++;

}

putc(0x0a); putc(0x0d);

}
/*void gsm_read()
{ m=0; r=0; lcd_data('R'); while(rd[r]!='\0') { putc(rd[r]); r++; }

putc(0x0a); putc(0x0d);

} */

void gsm_delay(unsigned int k)
{ unsigned int i,j; for(i=0;i<=k;i++) for(j=0;j<=1273;j++);
} void tx(unsigned char tx_data)
{ SBUF = tx_data; while(TI==0); TI=0;
}