system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are phone scammer that spoof caller ID unstoppable? Why can't telecom operators filter spoofed caller ID info the way data networks filter spoofed IP addresses?
gpt
Telecom operators benefit from spoofed caller id, it leads to more calls.  Network operators use the return IP to send answers back, so spoofing it doesn't get you any data.  They mostly check for spoofing because it's a symptom of evil.  Telecom operators are evil, so it's not on their list of problems to solve.