Caller ID originates from the sender and has no authentication. (Bell 303 modem modulation between the 1st and 2nd rings iirc.) I don't believe there is any oth

Caller ID originates from the sender and has no authentication. (Bell 303 modem modulation between the 1st and 2nd rings iirc.) I don't believe there is any other data with the call to know the calling number either. (I don't work in Telecom, so take it with a grain of salt as that's just the research I've done as an outsider.)