This is a quick glossary of "caller ID" varieties, by Stanton McCandlish,
mech@eff.org, Electronic Frontier Foundation Online Activist.

CNI, CNID - Calling Number Identification.  It's caller ID as we usually
            of it - the service individuals and businesses can buy from the
            telco; blockable by the caller usually with the code *67 on a
            per-call basis, and if you're lucky, even on a per-line
            permanent (but reversible) basis.  The FCC has proposed, under
            pressure from commercial interests, to ban per-line blocking. 
            CNID is not available in all areas, and is not fully compatible
            from one area to another.

CID - Caller Identification; non-technical synonym of CNID.

ANI - Automatic Number Identification - this is unblockable, and far more
      revealing - gives phone number, name, and address.  It is a basic
      "feature" of all 800 numbers, and probably 900/976 numbers as well in
      the U.S., and cannot be blocked by the caller.  It exists ostensibly
      to prevent fraud and to enable accurate billing, but is actually mostly
      used to collect personal information for commercial databases and
      mailing lists.  ANI works no matter where you live in the US, and
      possibly in Canada as well. (???)

AIN - Advanced Intelligent Network - rather vague and silly name for a 
      caller-id type "service".  Brock Meeks says of AIN: "Advanced
      Intelligent network is indeed used.  At least, I used to run
      across it all the time when I was working for CommDaily, it's in
      conjunction with SS-7 services.  hell, ask MCI about their AIN networks
      and how they've licensed that platform to the Canadians for "seamless"
      services between the two countries."

CLI, CLID - Calling Line Identification; synonym of CNID.

CPN, CPNI - Calling Party Number, Calling Party Number Identification. 
            Synonymous with CLI & CNID.

SS-7 - According to Brock Meeks of Communications Daily and CyberWire
       Dispatch, SS-7 [see AIN, above] is "not a 'service' but a
       *platform* on which Caller ID type services are built and delivered."


These definitions are not very precise, and I don't make any warranty as
to their perfect accuracy.  - mech@eff.org