Cpp code on Copy Constructor?

Copy Constructor
 

const double CALL_RATE = 1.0;

class Customer {
  int m_id;
  std::string m_name;
  std::string m_phone;
  double m_balance;

  public:
  Customer(int id, std::string name, std::string phone, double balance) {
    m_id = id;
    m_name = name;
    m_phone = phone;
    m_balance = balance;
  }
  Customer(int id, std::string name, std::string phone) {
    m_id = id;
    m_name = name;
    m_phone = phone; 
    m_balance = 500;
 }
 /*Customer(const Customer& ref) {
    m_id = ref.m_id;
    m_name = ref.m_name;
    m_phone = ref.m_phone;
    m_balance = ref.m_balance;
 }*/
 void makeCall(int nmins) { m_balance -= nmins * CALL_RATE; }
 void recharge(double amount) { m_balance += amount; }
 double getBalance() { return m_balance; }
 void display() { std::cout << m_id << "," << m_name << "," << m_balance << "\n"; }
};
int main() {
  Customer c1(1001, "Scott", "9800012345", 500.0);
  c1.makeCall(10);
  c1.recharge(100);
  // a1.display();

  Customer c2;

  Customer c3(c1);
  c3.display();
  return 0;
};