Config:

Edit <arduino ide directory>/hardware/arduino/avr/cores/arduino/HardwareSerial.h

Change:

#define SERIAL_TX_BUFFER_SIZE 64
#define SERIAL_RX_BUFFER_SIZE 64

To:

#define SERIAL_TX_BUFFER_SIZE 256
#define SERIAL_RX_BUFFER_SIZE 256

Edit <arduino ide directory>/hardware/arduino/avr/libraries/SoftwareSerial/src/SoftwareSerial.h:

Change:

#define _SS_MAX_RX_BUFF 64

To:

#define _SS_MAX_RX_BUFF 256

Create config.h:

#define SOFTWARE_SERIAL
#define DEBUG_MODE
#define MAX_BUFFER_SIZE 200
#define BAUD_RATE_SERIAL 9600
#define SS_RX_PIN 7
#define SS_TX_PIN 8
#define WAKEUP_PIN 2
#define MOSFET_PIN 12
#define PHONE_NUMBER "+98**********"