There is no such thing as phone number of origin. A business voice circuit doesn’t have an identity like that. Each call it carries is whatever the signaling da

There is no such thing as phone number of origin. A business voice circuit doesn’t have an identity like that. Each call it carries is whatever the signaling data says it is. There may be some inbound numbers routed to it, or not. The problem is not “is this the true phone number of this circuit?” because there is no such thing. It is not even “do I route inbound calls for this number down this circuit?” because there are legitimate topologies where you don’t. It’s the fully general “is this customer authorized to use this number?” which you somehow have to establish with a bunch of mutually distrusting competitors. It’s possible, that’s what STIR/SHAKEN is, but it’s a formidable problem. Telephony is much more complicated than your one-circuit-one-number residential POTS line.