c++ - How to read the last text message sent to the buffer(stored in SIM card)-Arduino -

i'm using fona 3g (sim5320e) arduino mega 2560.

i have buffer store text messages (sms) - char replybuffer [255]. i'm sending 10-digit phone number occupying 10 bytes in replybuffer per text message. suppose, have sent 5 text messages sim card , of them stored in replybuffer. how can read last 10-digit number or last text message in buffer can send sms last mobile number rather 1st mobile number done currently?

// setup routine runs once when press reset: #include "adafruit_fona.h"  #define fona_tx 11 #define fona_rx 12 #define fona_rst 9  // large buffer replies char replybuffer[255]; char buffer[50]; char r1[6];char r2[6];  // default using software serial. if want use hardware serial // (because softserial isnt supported) comment out following 3 lines  // , uncomment hardwareserial line #include <softwareserial.h> softwareserial fonass = softwareserial(fona_tx,fona_rx); softwareserial *fonaserial = &fonass;   // hardware serial possible! //  hardwareserial *fonaserial = &serial1;  // use fona 800 , 808s //adafruit_fona fona = adafruit_fona(fona_rst); // use 1 fona 3g adafruit_fona_3g fona = adafruit_fona_3g(fona_rst);  uint8_t readline(char *buff, uint8_t maxbuff, uint16_t timeout = 0);  uint8_t type;  byte readco1[] = {0xff, 0x01, 0x86, 0x00, 0x00, 0x00, 0x00, 0x00,0x79};  //command packet read co (see app note)  byte response1[] = {0,0,0,0,0,0,0,0,0};  //create array store response  byte readco2[] = {0xff, 0x01, 0x86, 0x00, 0x00, 0x00, 0x00, 0x00,0x79};  //command packet read co (see app note)  byte response2[] = {0,0,0,0,0,0,0,0,0};  //multiplier value. default 1. set 25 o2 25%  int valmultiplier1 = 1;int valmultiplier2 = 1;  void setup() {   while (!serial);    serial.begin(9600);   serial1.begin(9600);    //opens virtual serial port baud of 9600   serial2.begin(9600);   serial.println(f("fona basic test"));   serial.println(f("initializing....(may take 3 seconds)"));    fonaserial->begin(4800);   if (! fona.begin(*fonaserial)) {     serial.println(f("couldn't find fona"));     while (1);   }   type = fona.type();   serial.println(f("fona ok"));   serial.print(f("found "));   switch (type) {     case fona800l:       serial.println(f("fona 800l")); break;     case fona800h:       serial.println(f("fona 800h")); break;     case fona808_v1:       serial.println(f("fona 808 (v1)")); break;     case fona808_v2:       serial.println(f("fona 808 (v2)")); break;     case fona3g_a:       serial.println(f("fona 3g (american)")); break;     case fona3g_e:       serial.println(f("fona 3g (european)")); break;     default:        serial.println(f("???")); break;   }  } void loop()   { //get readings of sensors   sendrequest1(readco1);   int valco1 = getvalue1(response1);    sendrequest2(readco2);   int valco2 = getvalue2(response2); // timer initialization   static unsigned long starttime = 0;    uint16_t smslen; int16_t slot;      if (! fona.readsms(slot, replybuffer, 250, &smslen)) { // pass in buffer , max len!           serial.println("failed!");      }  //loop function deleting first byte upon second or latest byte arrival  if (valco1 < 5 && valco2 < 5 )    //        fona.deletesms(0);  // has been 1 minute since value below 5?           if (millis() - starttime > 1ul*60ul*1000ul) {           //sendalert();        //  memset(replybuffer, 0, sizeof replybuffer);         starttime = millis();        fona.sendsms(replybuffer, "got it"); }   serial.print("co1 ppm = ");   serial.print(valco1);   serial.print("  co2 ppm = ");   serial.println(valco2);  } void sendrequest1(byte packet1[]) {   while(!serial1.available())  //keep sending request until start response   {     serial1.write(readco1,9);     delay(50);   }    int timeout=0;  //set timeoute counter   while(serial1.available() < 9 ) //wait 9 byte response   {     timeout++;       if(timeout > 10)    //if takes long there error       {         while(serial1.available())  //flush whatever have           serial1.read();            break;                        //exit , try again       }       delay(50);   }    (int i=0; < 9; i++)   {     response1[i] = serial1.read();   }   }  unsigned long getvalue1(byte packet1[]) {     int high1 = packet1[2];                        //high byte value 3rd byte in packet in packet     int low1 = packet1[3];                         //low byte value 4th byte in packet       unsigned long val1 = high1*256 + low1;                //combine high byte , low byte formula value     return val1* valmultiplier1; } void sendrequest2(byte packet2[]) {   while(!serial2.available())  //keep sending request until start response   {     serial2.write(readco2,9);     delay(50);   }    int timeout=0;  //set timeoute counter   while(serial2.available() < 9 ) //wait 9 byte response   {     timeout++;       if(timeout > 10)    //if takes long there error       {         while(serial2.available())  //flush whatever have           serial2.read();            break;                        //exit , try again       }       delay(50);   }    (int i=0; < 9; i++)   {     response2[i] = serial2.read();   }   }  unsigned long getvalue2(byte packet2[]) {     int high2 = packet2[2];                        //high byte value 3rd byte in packet in packet     int low2= packet2[3];                         //low byte value 4th byte in packet       unsigned long val2 = high2*256 + low2;                //combine high byte , low byte formula value     return val2* valmultiplier2; } 

link download fona 3g library.

open fonatest program have @ different commands.