A difficult question and one that you really have to answer on your own, but how badly do you need to know who made the call?

If you have been receiving nuisance calls then you can just report them to your local police station and they will take it from there. If you trust them to pursue it then that should be the matter resolved. If you really want to be certain the appropriate action is taken then you need to get in contact with their phone provider. The police may not be able to do anything unless threats are made, but the phone company will take the matter seriously and it could lead to the person making the calls being disconnected.

The problem is you can’t phone their service provider without using a reverse cell phone website as without them then I don’t know of any other way of identifying who they are with (unless you phone their voicemail and they haven’t changed their message then sometimes you can tell from that). Even though there is a small charge involved then you can’t argue that the easiest option is to use one and dig up the service provider and the name and address of the person.

Now you are better equipped when you want to go to the police and report them as you can give their name and address, then just to make sure go to the phone company too.

That combo gives you the best chance of getting the person into trouble (just make sure it wasn’t a wrong number first!). That doesn’t necessarily mean the person will stop, they can get a new phone to call you from etc - but if you know the name of the person you at least have the upperhand and if you confront them with the evidence and let them know you will just keep reporting them then you are no longer being a faceless victim and most people are cowards and will just stop straight away.

ecomwizard.com