Block persistent callers immediately to disrupt their pattern. Document every incident, noting dates, times, and any messages left, as this builds a case for reporting. Register your number on national do-not-call lists to reduce unwanted contacts. If calls escalate, contact your telecom provider for advanced blocking tools or trace options. Consider apps that identify and silence spam. For severe harassment, report to authorities like the FCC or equivalent privacy body—evidence shows these outfits often rotate numbers to evade blocks, so proactive steps protect your peace.
I receive calls from this group frequently. After blocking one number, they contact me a week later from a new line.