Bomb threat at a high school "could not be traced by caller ID because it was a 'blocked' number."
I know inbound "800" numbers get ANI even on "Blocked Caller ID"
I could have sworn that there was a field called something like Responsible Billed Party that appeared in our DEX records. That contained the dialing number, and we turned it over to the police in the case of harassment of one of our employees, but the police said they couldn't use it without a search warrant. That was on a call forwarded to a voicemail, but I thought it was present on all of the calls. Maybe it was only on forwarded calls.<
- - Clarence A Dold - Santa Rosa, CA, USA GPS: 38.47,-122.65***** Moderator's Note *****
SS7 packets always contain the calling party ID, but the *DISPLAY* of that number is blocked at the terminating office if the "do not display" bit is set.
The person who received the call probably wasn't able to hit the code to report the calling number, since that capability is missing from most PBX extensions. However, the police can ask the LEC to search its billing records to find out which number the call was placed from - those are the "Local Usage Detail" records, which police refer to as "LUDs".
Most LECs keep usage records of all calls, for use in trunk planning, growth forecasts, sales campaigns, etc. However, the originating switch might not be capable of doing that, or may not have been programmed to keep such records.
Bill Horne Moderator