Regarding the recent thread about telemarketers, the state and federal laws regarding telemarketers, and "tracing" calls....
Note that the "Call Trace" feature, 11-57 or *57, which is intended only for serious harrassment threats (i.e., death threats and the like), where a report is sent to telco and/or law enforcement for further investigation -- and the person using the feature also has to "follow up" with telco (usually by calling an automated reporting line)...
I tend to think that *57 / 11-57 "Call Trace" is SS7 "Caller-ID" based, and NOT using ANI. If there is no C-ID info passed via SS7 from the originating end, or if it is invalid (invalid area and/or office codes, something less than ten "NANP" digits, strings of 1's or 0's, etc) or of a "valid" NANP format (with valid area and office codes) but still a "forged" (phony) number (either an unassigned line-number or even fraudulently sending-out someone ELSE'S real number as SS7-based C-ID), then the Call Trace feature is of little value.
While ANI can be sent all the way to the far-end in some cases where facilities are ordered for ANI, such as big-volume 800/888/etc. numbers who order "realtime" ANI delivery (and I doubt that someone can "forge" outbound ANI, but then again....), ANI delivery usually doesn't go all the way to the far-end central office. ANI is sent from the originating central office to a telco/LD billing platform or operator platform (CAMA, TSPS, TOPS, OSPS, etc), and a 911 PSAP.
And ANI might not always give the EXACT number of someone on a PBX but rather the overall billing number(s).
Anyhow, if there's an actual *TELCO EMPLOYEE/RETIREE* expert out there who has "firsthand" knowledge of *57 / 11-57 "Call Trace", does it use SS7-based C-ID? (which is frequently "spoofed"), or does it use ANI delivery?