GSM SM5100B C M E R R O R: 4 błąd

Używam Arduino do sterowania urządzeniem GSM SM5100B, wszystko działa z wyjątkiem sytuacji, gdy chcę wysłać SMS po otrzymaniu innego. Rozumiem,

Kod błędu:

O K> + C M G S: 2 5 O K + C M E E R R O: 4

Mój kod do obsługi wyżej wymienionych otrzymanych wiadomości SMS:

     #include <SoftwareSerial.h>  //Include the NewSoftSerial library to send serial commands to the cellular module. 
        char inchar;                //Will hold the incoming character from the Serial Port. 
        SoftwareSerial cell(2,3); 
        char mobilenumber[] = "0597010129";
        void setup() { 
        //GSM
        Serial.begin(9600); // opens serial port, sets data rate to 9600 bps
        Serial.println("Initialize GSM module serial port for communication.");                       
        cell.begin(9600); 
        delay(35000); // give time for GSM module to register on network etc. 
        Serial.println("delay off");
        cell.println("AT+CMGF=1"); // set SMS mode to text 
        delay(200); 
        cell.println("AT+CNMI=3,3,0,0"); // set module to send SMS data to serial out upon receipt 
        delay(200); 
        } 



        void loop() {   

         if(cell.available() >0)//If a character comes in, from the cellular module
         { 
         inchar=cell.read(); 
         Serial.println(inchar); 
         if (inchar=='#'){ // OK - the start of our command 

           delay(10); 
           inchar=cell.read();
           Serial.println(inchar);  

             if (inchar=='a'){ 

               delay(10); 
               Serial.println("The folowing SMS : \n");
               inchar=cell.read();
               Serial.println(inchar); 

               if (inchar=='0'){ //sequance = #a0

                 Serial.println("#a0 was received"); 

             }
             else if (inchar=='1'){//sequance = #a1

                Serial.println("#a1 was received ");
                sendSms();

             }
         }
         cell.println("AT+CMGD=1,4");// AT command to delete all msgs
         Serial.println(" delete all SMS"); 
          } 
        }//end of  if(cell.available() >0) {...}
        }

        void sendSms(){
        //cell.println("AT+CMGF=1"); // set SMS mode to text 
        cell.print("AT+CMGS=");  // now send message... 
        cell.print((char)34); // ASCII equivalent of " 
        cell.print(mobilenumber); 
        cell.println((char)34);  // ASCII equivalent of " 
        delay(500); // give the module some thinking time 
        cell.print(":D hello m3alleg :D");   // our message to send 
        cell.println((char)26);  // ASCII equivalent of Ctrl-Z 
        delay(20000);
}

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