How to record and display full ANI/Caller-ID?

February 3, 2009 3:02 PM

How can I record the full ANI signal (caller-ID) incoming and display its content, separate of whether the privacy bit is set or not?

From what I've read, the Caller ID signal that runs in most US residential markets (ie: Verizon) may display "Private" (based on a flag set to 0 or 1), though the actual full number is still transmitted in the ANI stream. Modern devices are programmed to display "Private" when this privacy flag is set.

If that's correct, it's reasonable to assume one could craft their own hardware (or software) to capture the full Caller ID signal and display.

Curious if someone has more info on this....

posted by forrie to technology (4 comments total)

In-band CID data is not ANI. Your residential line is not being fed ANI (which is out of band and thus by definition isn't on your line). You'll have a lot better luck with your googling when you leave ANI out of it entirely since it has nothing to do with what you want.
posted by majick at 3:09 PM on February 3

WATS (toll-free) lines include ANI, IIRC.
posted by rhizome at 3:14 PM on February 3

If you have a standard analog residential phone line, I do not believe that the calling party number of blocked calls is sent down your line during the Caller ID burst. The ANI is sent (via SS7) to the Verizon switch that your line is connected to, but the switch sees the private flag, honors it, and does not send the number to you when it rings your line.

If you had digital service from the phone company -- possibly ISDN BRI, but more likely CAS/T1 or ISDN PRI -- you would be more likely to receive the full ANI record from the telco with the private flag set. It would then be up to you and your equipment to decide whether to honor the private flag.

Some VoIP service providers, which typically do receive the full ANI, decide not to honor the private flag and sends the ANI to you in the call setup message to your equipment. Obtaining an account and a DID (inward dialing number) from such a service provider is typically the easiest way to see the ANI data for CallerID-blocked calls for a home user. In order for this to work, you would need to either port your phone number to the VoIP provider or entice the unknown caller to call your new VoIP-provided number.
posted by Juffo-Wup at 3:16 PM on February 3 [1 favorite]

Thank you, both people, this clears things up a lot. Clearly I did not understand the difference between ANI and Caller-ID, believing it was synonymous.

That being said, at the moment I have a Verizon land line -- I don't use it that frequently. Comcast is my network provider -- I don't care for their phone service, that's another topic.

It seems I could do more, with less, if I had a VoIP account that I could port the number to, AND access it from anywhere on the Internet (say, some portable device I tote with me). That's another topic.

Thank you again, I appreciate it.
posted by forrie at 8:47 PM on February 3