Yes, it isn't being paranoid, this is what happens. If you respond in any way, even to tell them to stop, it confirms the number as an active number and your nu

Yes, it isn't being paranoid, this is what happens. If you respond in any way, even to tell them to stop, it confirms the number as an active number and your number then becomes valuable. They then either won't let up on contacting you or will sell your now confirmed/valuable number onwards to people that want to buy active numbers for their own, usually nefarious, purposes.