&gt;&quot;Caller ID&quot; isn&#x27;t the &quot;source of the message&quot;, just some data transmitted along with the ringing sound, and as you can see the circuit doesn&#x27;t have a globally unique identifier. &#x2F;&#x2F;<p>The companies could enforce the side channel info as the actual call origin, but they don&#x27;t want to. Just like snail-mail spammers they&#x27;re paying more money than residential customers will pay to require that info.<p>It&#x27;s broken because it serves the purposes of the phone companies to keep it that way. This is what you get by detaching profit from ethics.<p>I&#x27;d settle for my phone company dropping calls with spoofed caller ID  - like 0, my own number, foreign calls with local numbers, local numbers that don&#x27;t even terminate, etc..<p>Indeed I think origin should be legally required even if it&#x27;s &quot;K phone network&quot; - I don&#x27;t mind blocking all calls via companies that service spammers.