It is unethical to use Truecaller app

Let's begin by analyzing what makes something ethical or not. I hope that Pro is not a non-consequentialist whom would state that any act or concept can be inherently wrong or right regardless of context or intended outcome. If this is the stance of Pro then I ask them to explain why they bothered taking a semi-consequentialist approach to explaining the immorality of using Truecaller app. Ethics, at their core, are simply the study of what the pinpoint edge of the fine line between right and wrong should be and why it is so. Truecaller requiring the user to give them their phonebook and details is not relevant to the debate. Using the app could not be unethical to yourself since you are consensually giving that information to help the app better locate you contacts to others who may be getting unknown rings from them. Now let's look into the case of harassment. If someone you do not know is harassing you by calling you over and over and will not seize phoning you, Truecaller is basically your only hope since contacting the police about it would result in them literally using tech at their disposal which would be spending taxpayer's money on what Truecaller would do for you for no tax money at all. This in itself makes it both understandable in intention and more moral in outcome than the alternative method in the possible ethically different paths you could endeavour. What is also important to consider is the concept of unknown numbers in the first place. If you are ever ringing someone alone you are doing something identical to accessing a website on a proxy server or via VPN. While mild paranoia on the masker's part can be a benign motive for this to prevent being tracked and harassed (making the act of being 'unknown' defence-only and thus moral/ethical) what is far more likely to drive someone to such measures, even people using it in a primarily defensive manner, is the joy and/or pleasure of knowing that any and all times you call someone you are at a severe upper hand if the conversation ever turns ugly. You know their number and with that can track them in a variety of ways more than they can ever do back to you. This is possibly 'fair' to someone who has fully knowledge and capability to make their number unknown but let's think about this for a minute; even someone who has set their phone to 'unknown' and tries their very best to prevent anyone finding them cannot hide their number if the other person is the one calling them. Truecaller is nothing more than a defence against people intentionally denying your ability to defend against them if they begin to give you reason to feel the need to do so thus Truecaller is nothing more than a danger to those seeking to cause it. While Truecaller can be used to assist in tracking someone down, the only time when someone could ever appear ‘unknown’ to you is if they are the one doing the calling and the only time you would need their number to track them down would be if you didn’t know who they were at all on top of not knowing their number. If someone who you do not know is calling you (which is the only reason to use Truecaller) then they are clearly a danger or nuisance. If you are using it to confirm that who they say they are is who they indeed are then it’s neither moral nor immoral/unethical. It is simply something you can use to then do malice or defend against it.