void timer_handler(int signum)                                                  
{                                                                               
                                                                                
    pthread_t updateThread;                                                     
                                                                                
    sem_wait(&semCounters);                                                     
                                                                                
    counter.t1++;                                                               
    counter.t2++;                                                               
    counter.t3++;                                                               
    counter.t4++;                                                               
                                                                                
    if(counter.t4 >= 30 && flag == 1)                                           
    {                                                                           
        if(ret == 1)                                                            
        {                                                                       
            if(DEBUG)                                                           
            {                                                                   
                printf("GPRS General Interrogation RETRY flag set.\n");         
            }                                                                   
                                                                                
            counter.t4 = 0;                                                     
                                                                                
            pthread_create(&updateThread, NULL, thread3Function, NULL);         
        }                                                                       
                                                                                
        else                                                                    
        {                                                                       
            counter.t4 = 0;                                                     
        }                                                                       
    }                                                                           
    sem_post(&semCounters);                                                     
}