Talk:Caller ID

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Arb heading[edit]

Section cut from main article

--Misleading/Incorrect Information-- This article suggests that caller name (or cnam) and telephone number id are the same service. They are not. Telephone number ID is a standard SS7 service that displays the ANI or calling number. CNAM requires an SS7 query to a database of names associated with those numbers. This is why it's common in many areas to view the number of a caller, but not the name, or possibly receive city/state or "anonymous" as a name. The two are related by SS7, but they are not the same service.

Spoofing and falsification[edit]

In August 2004, a company called Star38 announced that it would offer a service in the U.S., which would allow subscribers to falsify the name and/or number they are calling from. The idea came from hackers, who have been using VoIP to spoof numbers as pranks. The vulnerability comes from the trust-based design of caller ID, whereby the telephone exchange receiving the call trusts the sending exchange to provide the correct number, and the sender trusts the receiver to keep the number private, if it is indicated as a blocked or anonymous number.

The exploit uses digital telephone lines of private branch exchanges, which have been able to alter their outgoing CID information for years because they are a "trusted" part of the CID system. Likewise, they can also ignore the "private number" flag for incoming calls. Star38 will allow subscribers to have this information passed along to their own phones, and will be controlled via the web. Star38 says it will limit the service to private investigators, collection agencies and the like, and will charge $20 per month and 7~10¢ per minute.

There is some useful information here, but if it is in the US, why not put it in the automatic number identification article. 'Announced' is really enough to warrant a mention, and no one needs the advert. -- Solipsist 19:12, 1 Sep 2004 (UTC)

I actually came here today to see how updated Wikipedia was on this. Apparently the guy between Star38 has decided to sell his business after 3 days online. He claims that he received death threats from hackers opposing commercialization of this technology / vulnerability. I think that the section should be structured the other way around. It should first discuss the spoofing technique was discovered and when it was first publicly demonstrated (I know that it was demonstrated at the H.O.P.E. conference in New York in June/July). Then, it should move on to talk about Star38's commercial implementation of the technique. — David Remahl 23:10, 4 Sep 2004 (UTC)
Interesting. The trouble is that this information is a little tangential to explaining what callerID is. However, it sounds like there is enough here for an article on 'caller ID spoofing' itself and link from this page - it sounds like it is a continuation of the history of phone phreaking. -- Solipsist 22:21, 5 Sep 2004 (UTC)


Why am I redirected to this page when I type in *67? The page makes absolutely no mention of it. preceding unsigned comment by (talk • contribs)

Good question. Looking at the history of the redirect page, it was originally redirected to Last Call Return then switched to point here. At a guess this is a code some telcos use to return the CallerID of the last call received (in the UK the code is usually 1471). I'm not sure it is a particularly good redirect to have it would probably be better to have these codes in a table on one page with links to pages describing the appropriate services and some explanation of the telco's / territories where they are used.
*67 IS currently explained in the article. However, I have noticed recently that I can dial *67 and dial a local # and still have them identify the # I'm calling from. In particular, from a 510 land line, I dialed *67 followed by (implicit 1-510) 355 9906, a local # for; I then made a call and the called party received the # I was calling from (I tested it by calling my cellphone). Onesuite recognized the # I was calling from and let me bypass PIN entry as well. While it's a nifty feature, it isn't helpful when I want to make calls w/o revealing my phone #, and I would think it's against the 'rules' that govern the local phone co, AT&T. —Preceding unsigned comment added by IReceivedDeathThreats (talkcontribs) 22:44, 24 June 2008 (UTC)

NOTHING ABOUT MOBILE CALLER ID- it's been available for 4 years! —Preceding unsigned comment added by (talk) 15:33, 5 January 2010 (UTC)

See Also[edit]

There seems to be a lot of text in the "See-Also" section. Wouldn't it be better to put most of this into appropriate sections? Perhaps I will when I get time. The Slimey 20:03, 19 June 2006 (UTC)

Too much material in the introduction[edit]

There's way too much material in the introduction, i.e., before the first section break, appearing before the table of contents. It seems to launch directly into a technical history of the implementation of this feature. Instead, the introduction should be a short definition of the term, plus maybe a short summary of the most important information imparted in the article. --Teemu Leisti 22:04, 28 July 2006 (UTC)

Yeah, I noted that, and split it up into more managable chunks, but the article is still way too heavy on the technical jargon. Aaack. I would rewrite the entire article, but as I don't know much about Caller ID, I'll leave that task to the technical expert. Hbdragon88 06:34, 29 July 2006 (UTC)
Looks better now. --Teemu Leisti 15:10, 3 August 2006 (UTC)
Still too top-heavy to me. Telemarketing-specific information seems to deserve its own subheading, and move it out of intro. Also several issues related to CID and telemarketing could be added, such as legal requirements (in the US) that CID can not be blocked, and use of CID-base advertising. I also agree with the sense that there is too much technical info intertwined in the general information. I would propose a separate heading of "Technical Information" and move history and tech info under that. I volunteer to clean it up next month unless I see some objections. --NoBiggie 16:40, 13 April 2007 (UTC)
Seeing no objections, I have cleaned up things, and moved the overly-technical information out of the intro (added by Ss7guru). I also deleted the paragraph 10 also added by Ss7guru which lacked neutrality and was really an unsupported plug for the telemarketing industry to be allowed to spoof. I added a "Legal" section with citations. Rather than one giant edit, I'll come back later and do more cleanup. NoBiggie 15:05, 12 July 2007 (UTC)

Why *67 *82[edit]

Of all the numbers availabee, why were *67 and *82 chosen for blocking and unblocking caller id. 82 represents letters UB which could be short for Un Block, but not sure what 67 would be No Send? Anyone know how these got chosen?

Perhaps *67 is MP (make private). At least that's not a bad way to remember it. My guess is the real reason for *67 is probably historical and has nothing to do with the letters. —Preceding unsigned comment added by (talk) 01:04, 8 September 2010 (UTC)

Definition of "hacking"[edit]

"Using services like Vonage or Skype, calling from a payphone, or using a calling card are easy means to fool caller ID." How on earth does this constitute hacking the caller id system? At most it is circumventing. Shouldn't the header be changed? Nichlas 10:14, 8 January 2007 (UTC)

Duplicate section?[edit]

  • 67 is mentioned both in blocking and disabling with very similar wording. Is this duplication necessary?

Much confusion over CID, CLI, ANI, CPN, Caller Name, CNAM, etc.[edit]

In this wiki page and many others I have seen, there seems to be much confusion over the difference between these items. I'd like to see some consensus on the proper use of these terms. It's inconsistent use is, in my opinion, one of the reason a lot of these articles are more confusing than they need to be. I'd be happy to grab my SS7 manuals to help. To start:

CPN (aka CgPN) = Calling Party Number. This is the directory number assigned to the person who makes the call.

CLI = Calling Line Identity. The phone number used for Caller ID service. This is almost always the CPN of the caller.

Billing Number = This is the phone number of the party responsible for origination billing for the call. On a typical home residential POTS service, the Billing Number and Calling Party Number are the same number. However, on multi-line systems and more complex systems, Billing Number and Calling Party Number are often different.

Billing Account Number = This is a customer ID used for billing telephone services. Historical telephone companies use a real phone number for this. Some use a "false" 10-digit number that is in the form of a telephone number. Other use a BAN that does not appear to be like a telephone number. For some telephone companies Billing Account Number and Billing Number are the same thing. On some they are not. The key here is that a Billing Number is always a real routable telephone number. A Billing Account Number might or might not be a telephone number, depending on the telephone company.

Caller ID = It is a service where the CLI is sent to the person receiving the call.

CND = Calling Number Delivery (CND) a the technical SS7 service that is often used for moving Caller ID information (CLI, PI, etc.) along with the call. (Until VOIP came around, SS7's CND was pretty much the _only_ way to get Caller ID.)

CID = CLASS code name for Caller ID service. (need to absolutely verify this one.)

ANI = Automatic Number Identification. This is a historic service similar to caller id, but sends Billing Number not CLI. It also often includes sending other information such as DNIS (dialed digits.)

Caller Name = This is a service. It passes a text description of the CLI.

CNAM = This is a 15 character text field used in Caller Name service. I've also seen it refer to CLASS feature code for Caller Name. This is confusing if standard. I recommend saying "caller name delivery" when referring to the service.

Presentation Indicator = this is data indicating whether caller id service should be blocked.

There are actually dozens more terms, but I'll stop here. If wanting more, pick up a Newtons Telecom Dictionary.

I suspect some confusion stems from common mis-use. It's common to hear: "I saw your caller id on my phone." It is more correct to say "I saw your phone number on my phone's display." Or if you want to be technical: "I saw your CLI on my phone (due to CID service.)"

I also suspect some of the confusion is because many PBX vendors, who should know better, also mix up the terms. They say stuff like "this allows you to get the ANI". They should be saying "this allows you to get Billing Number through the ANI service." Even worse: sometimes the PBX vendors mix up ANI and caller ID services; which are entirely different services.

Why is this important? Because the engineers are speaking slightly different language than your everyday person. It's only slightly different which means that the common reader is somewhat confused but not entirely sure why.

I realize that Wikipedia is not the same thing as a Dictionary, but recommend:

  • Start using the terms consistently throughout all articles.
  • Include some quick intros for the terms at the beginning. Something short and clarifying.
  • Either don't redirect "Caller Line Identification" to this particular page, or explain the difference between CLI and Caller ID right at the top of the article. Caller ID sends CLI. They are related, yes, but not the same thing.

And lastly, if you ever hear someone say "caller id sends ANI", please send them to this discussion page. ANI is a service, not a data item that can be sent. And it's not related to caller ID.

Discuss? SeptemberWizard (talk) 21:37, 10 March 2008 (UTC)

EXCELLENT! I agree. I have avoided trying to improve this article in the past because of this issue. The article actually contains several inaccuracies that are difficult to explain because a great number of people do not accurately understand all the terms defined above. A notable example is "Caller ID is also known as calling line identification (CLI) when provided via an ISDN connection to a PABX," (the beginning of the main part of the article). Part of the Caller ID service is the delivery technique - modem communication between the 1st and 2nd rings of an analog POTS line. Hence, the references to ISDN and a PABX are totally erroneous when discussing Caller ID. I suspect the confusion comes from the lack of understanding about the difference between the Caller ID and ANI services. ANI, today, is typically delivered over an ISDN PRI to a PABX.
One additional point (and not as important for the discussion above), you implicitly defined DNIS as "dialed digits". I don't have a telecom dictionary handy but I suspect you will find that it to is a service not a data item, Dialed Number Identification Service. Many people refer to the data item as "the DNIS (infomation)" or "the dialed digits" but I don't recall which, if either, is correct. Historically, the service delivered the actual dialed digits but today it typically delivers an identifier, a collection of digits derived from the dialed number. Like ANI, it too is typically delivered over an ISDN PRI to a PABX. Bellhead (talk) 02:16, 11 March 2008 (UTC)


International Standards[edit]

In typical US-centric fashion, this article is completely lacking in information about Caller ID signal standards outside the US. What about DTMF caller-id signalling for instance? (talk) 13:12, 9 August 2008 (UTC)

I don't know what you mean with "DTMF caller-id signalling" but the article is indeed very US-centric and might confuse people in most other countries with higher standards as concerns supplementary services. —Preceding unsigned comment added by (talk) 16:19, 21 November 2010 (UTC)

Updated for neutrality[edit]

Removed references to Vonage, replaced with ITSP (Internet Telephony Service Provider) since Vonage is not the only company to offer such VoIP egress services to the PSTN for neutrality. —Preceding unsigned comment added by (talk) 19:02, 9 December 2008 (UTC)

Getting around Caller ID blocking[edit]

Apparently TelTech is releasing a new phone that allows people to see caller ID even for blocked callers. The article above might be useful as a ref here, for stuff about how caller ID blocking works and information on who advocates it (for example, there's stuff about how it's used for protection of women fleeing domestic violence). rʨanaɢ talk/contribs 11:56, 17 February 2009 (UTC)

The Original Caller ID Service versus Generic Calling Line Identification[edit]

Is is just me of does anyone else see the corruption of this article caused by the differing interpretations of the term "Caller ID"?

"Caller ID" was originally a marketing term for a new service for POTS lines (only) that delivered the calling line identification information to the called line between the first and second rings using Bell 202 modem technology. In common usage it has become synonymous with the general concept of calling line identification. Both are valid topics but many editors of this article either do not understand the difference or do not realize that this article was originally about the POTS service. (For anyone confused about the distinction, read the "Much confusion ..." section above. You might also gain some additional insight by reading the article "Automatic number identification" which talks about a different calling line identification service. The "Automatic number identification" article has not yet been corrupted by a similar confusion.)

Should this article be split into two, with names like "Caller ID Service" and "Calling Line Identification"? Each would require a clear introduction and have an appropriate reference to the other.

Comments? Bellhead (talk) 18:06, 25 February 2009 (UTC)

CLIP redirects here[edit]

What is CLIP? The acronym is not mentioned in the article.-- (talk) 10:49, 2 April 2009 (UTC)

Bad Wording[edit]

"A video of his prototype was used to leverage the feature from the central office to the telephone set."

What does that mean? Could someone who knows please reword? Długosz (talk) 16:07, 17 July 2009 (UTC)

Caller ID not working[edit]

See WP:NOTFORUM - this is not the place for this. AndyTheGrump (talk) 00:58, 20 June 2013 (UTC)

Cellular (Wireless) Networks

Other than the technical, and engineering, professionals who work in the wireless area of technology, Few, if any, have any idea of how a wireless call is structured and the problems inherent in cellular call technology. To the average person, a cell phone is a convenient piece of technology, and how it works is of no concern. (Until of course, it fails to function.)

For those who would like a somewhat simple explanation of how cellular networks function, I have attached the following FAQ’s.

Q.) Why does my signal (the bars indicating signal strength) go up and down, even when I am close to a cell tower? A.) There are several factors that can affect your signal strength, The first being orientation of your cell phone. If you turn around in a circle watching the signal indicator on you phone, you will see it increases, or decreases, according to which direction you are facing. Another factor may be atmospheric conditions. even wind can affect signal strengths.

Q.) Why does my caller ID not work all the time? A.) The most common reason is because the caller is a telemarketer. The next most common reason is that your call is going through a tower that belongs to a different service provider, The other provider uses different equipment, and formats the call differently, which often does not include the caller ID. Another reason is that the caller, is using a different provider than you are. Again, different types of equipment, and call formats. The next most popular reason is that even if you and your caller, are both using the same provider, you may not receive a caller ID. The reasons behind this are that your provider wants you to be able to complete your calls, so if a cell tower is not working for some reason, (or is filled to it’s call handling capacity) your provider will route you to a cell tower in your area that is working, but it may belong to a different provider than the one you use. Again the different equipment, and call formatting. Unknown to the general public, A cellular call (From cell phone, to cell phone) connects to a cellular tower, (Cell Site) the cellular tower then connects to the PSTN (Public Switched Telephone Network) The call is no longer wireless once it leaves the cell tower and travels through the PSTN. Once the called cell phone is located, the call is routed through the PSTN to the closest cell tower, where the call once again becomes wireless and connects to the called cell phone. This call could go through dozens of different carriers in it’s passage through the PSTN. For example, Say I live in Los Angeles, and my brother lives in New York. Now if I place a call to my brother in New York, My call will flow through like the one described above. Now say I go to visit my brother in New York, I go out to see the sights, while my brother goes to work. I get lost and call my brother for directions. For me to place this call, the local cellular network ‘sees’ my cell phone as a Los Angeles number, My call to my brother (two blocks away) now goes all the way back to Los Angeles. (cell site-PSTN-cell site) where my phone is registered. There my local cellular provider database makes sure that my phone is a valid customer and calculates billing base on where I am calling from, and, where I’m calling to. The call to my brother is then sent back out to New York. Another cell site-PSTN-cell site call. (even if your provider is global, the call goes to the cell site where your phone is registered) Now I have a call that goes from New York to Los Angeles, through Los Angeles and back to New York, to talk to my brother two blocks away. Isn’t that incredible? Two long distance calls, to talk from two blocks away.

Q.) How does the PSTN work? The PSTN (Public Switched Telephone Network) is somewhat incomprehensible to the public. (and a lot of Telecommunications professionals) Basically In a broad sense, the PSTN is very simple, and extremely complicated in a detailed sense. The way it works is that when you originate a call, (cellular or land line) your local telephone company (Telco) analyzes your call, based on the digits you dialed, then looks for a route to send the call to it’s destination. Your local Telco may have from one (1) to twenty (20) routes to place the call over. The route to be picked is based on how heavy the traffic is on the routes being considered. Once a route is picked the call is sent to the next location. Which may or may not be the same Telco you are using. The call is then picked up by that Telco, and the process of picking a route begins all over again. All this is handled electronically and is very fast. Users do not notice that this is happening. This process is repeated until the call reaches it’s destination. This call, Let’s say it is from Miami, Florida, to Atlanta, Georgia. This call could travel from Miami to New York, to Toronto, to Chicago, to Los Angeles, to Dallas, to get to Atlanta. All of it being handled electronically. No one really knows where this call travels to get from one point to another. It may travel between Telco after Telco after Telco, to reach the destination point. It may change format several times, and go through hundreds of pieces of equipment to complete the call. The call may change from analog to digital, from copper wire to optical fiber, etc. This is a very, very, simple explanation of the PSTN —Preceding unsigned comment added by (talk) 19:30, 6 November 2009 (UTC)

WOW! What a bunch of misleading information with regard to call routing - both cellular and wireline. Bellhead (talk) 21:57, 12 November 2009 (UTC)

'History' section[edit]

This section needs substantial work, in my opinion - for a start, it needs proper sourcing, and the table of Theodore Paraskevakos's patents needs to go. If he played the significant part in the development of caller ID that is claimed, it should be possible to verify it in secondary sources - as it stands, it simply cannot be verified. AndyTheGrump (talk) 00:57, 20 June 2013 (UTC)

I've now removed the patents table - there really can't be any justification for this. Note that we need a proper source for the assertion that these patents pre-date all others - if one cannot be found, the statement will need to be removed. AndyTheGrump (talk) 13:35, 20 June 2013 (UTC)

CNAM lookup via web page?[edit]

There are some resources online for doing a CNAM lookup from a website. Some good, some bad. Could a few of the better ones be referenced in this article?

So far, the best one I have found is and there are others that may be as good or even better. GeoFan49 (talk) 22:30, 20 December 2014 (UTC)

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Checksum error handling?[edit]

Can we add details of how checksum errors are handled?

I ask because my (Google Voice/GV) phone # just received a couple calls that GV recorded as being from a 5 digit phone #: 216007 (which is not a valid short code). I picked up both times and heard no response. I noticed that the first two digits were the beginning of the area code for, and the last 4 digits were the last 4 digits of, my Mom's land line #. I called her and asked if she had just called, and she said she had. I'm wondering how this glitch most likely happened. I see some mention of checksums in the Caller_ID#Type_II_caller_ID section. If a checksum fails, a "?" could/should/would indicate a digit was unknown, and so in these cases, 21????6007 would be displayed, rather than 216007, no? Also odd that two calls in short succession would hit the same glitch?!-- (talk) 20:27, 28 July 2018 (UTC)