OCP

Phone.cs

public class Phone
{
    public PhoneType Type { get; set; }
}
public enum PhoneType
{
    Iphone,
    Samsung
}
public class Iphone : Phone
{
    public Iphone()
    {
        this.Type = PhoneType.Iphone;
    }
}
public class Samsung : Phone
{
    public Samsung()
    {
        this.Type = PhoneType.Samsung;
    }
}