GSM garage door opener (Siemens TC35i + Arduiono mini pro)

#include <SoftwareSerial.h>                     //Including Sotware Serial lib for second serial port to connect Siemens TC35i

String tel_1 = "+11221234567";                  //Telephone number 1
String tel_2 = "+11227654321";                  //Telephone number 2

String temp;                                    //Define temp string

int rxpin = 9;                                  //Define rx and tx pin
int txpin = 8;

byte door = 10;                                 //Relay output

SoftwareSerial serial2(rxpin,txpin);            //RX,TX

void setup() {

    pinMode(door, OUTPUT);                      //Set relay port to output
    digitalWrite(door, HIGH);                   //Set relay port to high (switch relay default state)

    Serial.begin(115200);                       //Initialize HW serial port for debug
    serial2.begin(57600);                       //Initialize SW serial port for communicat with modem

    Serial.println("Starting....");             //Program starting

    delay(120000);                              //Waiting for modem (120sec is enough)
    serial2.println("at");                      //Send AT Command
    Serial.println("at");
    temp = serial2.readString();
    Serial.print(temp);
    delay(1000);

    Serial.println("at+clip=1");                //Send AT Command to receiving caller ID
    serial2.println("at+clip=1");
    temp = serial2.readString();
    Serial.println(temp);
    delay(1000);

  Serial.println("Enter to loop...");           //Loop is stating...

}

void loop() {

      digitalWrite(door, HIGH);                 //Set relay outpout to high (relay normal state)

    if (serial2.available()) {                  //Wait for SW Serial communication is active
        String str = serial2.readString();      //Read out full string from SW serial
        temp = (str.substring(18,30));          //Parser out from onyl Caller ID
        Serial.println(str.substring(18,30));   //Show Caller ID (only ID, without any text. Example: RING ect..


     if (temp == tel_1)                         //Find caller id in database
     {
        Serial.println("Telephone number 1");   //Print caller id in debug port
        serial2.println("AT H");                //Hang up the call/ring
    dooropen();                                 //Open the door
     }

     if (temp == tel_2)                         //Find caller id in database
     {
        Serial.println("Telephone number 2");   //Print caller id in debug port
        serial2.println("AT H");                //Hang up the call/ring
    dooropen();                                 //Open the door
     }


     else {
        Serial.println("Unknow number door sill locked"); //Print to debug port
        serial2.println("AT H");                //Hang up the call/ring
        temp = serial2.readString();            //Eliminate "OK" feedback to AT H command

     }

   }

}

void dooropen()
{
  Serial.println("Opening the door");           //Print to debug port
  digitalWrite(door, LOW);                      //Set relay output LOW, activate the relay
  delay(1000);                                  //Wait 1 sec
  digitalWrite(door, HIGH);                     //Set relay output HIGH, relay normal state
}