Directory assistance

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In telecommunications, directory assistance or directory enquiries is a phone service used to find out a specific telephone number and/or address of a residence, business, or government entity.


Directory assistance systems incorporate a wide range of automation to reduce the cost of human operators. Almost all systems use custom database software to locate listings quickly.

Most directory assistance systems use automated readback systems to give out the phone number. This frees the directory assistance operator to move on to another caller as soon as the correct listing is located.

Some systems have "store and forward" technology which records "city and state" the caller is requesting and then plays the city and state speech to the operator before they come online and then say "Residential or business listing?" or simply "What listing please?"

Interactive voice response systems have been added to many directory assistance systems. These complex systems use speech recognition and recorded speech or speech synthesis to handle the entire call without live operator intervention.

Most systems recognize location and listing. If recognition confidence is high, the best result is played to the caller. If confidence is low, the caller's request is played back to a live operator, who locates the correct listing.

North America[edit]

In the North American Numbering Plan (covering Canada and the United States), directory assistance may be contacted by dialing 4-1-1 (one of the N11 codes) or to get a listing in a remote or non-local area code, directory assistance is available at 1-area code-555-1212 or online at 411 Directory Assistance[1]

However, a 411 landline call will provide local listings as well as nationwide listings and sometimes international listings.

Most telephone companies permit up to two listings per 411 call. All wireless carriers offer nationwide listings with 411, and some offer additional Enhanced Directory Assistance services. However, wireless numbers for residential customers are not available via 411.

Rate classes[edit]

U.S. wireline telephone companies classify DA into four rate classes:

  1. 411 LDA — Local Directory Assistance. 411 is dialled and the operator is requested to search for a listing in a group of area codes "LATA" local to the caller. Example: the caller lives in area code 630 (Oak Brook, IL) and request a listing for a business in area code 312 (Chicago, IL). In this case, AT&T Illinois bills the call.
  2. 411 NDA — National Directory Assistance. 411 is dialled and the operator is requested to search for a listing in an area code not local to the caller. Example: The caller lives in area code 630 (Oak Brook, IL) and requests a listing for a business in area code 213 (Los Angeles, CA). In this case AT&T Illinois bills the call.
  3. (area code) 555-1212 — National Directory Assistance. This example assumes the caller is in Oak Brook, IL (area code 630) and uses Verizon as their long distance carrier. Example: The caller is looking for a listing in Los Angeles, CA (area code 213) and dials 213-555-1212. In this case Verizon bills the call.
  4. 00 and ask for the international directory assistance operator. AT&T provides International Directory Assistance calls. See for additional information and country and city codes.

Toll-free directory assistance[edit]

In the U.S., directory assistance for companies with toll-free "800 numbers" (with area codes 800, 844, 855, 866, 877, and 888) is available from toll-free directory assistance.

Toll-free directory assistance is provided by telecommunication providers, namely AT&T and Verizon, as mandated by the Federal Communications Commission. Companies must request to have their toll-free number listed and pay the providers each time their phone number is released to a Toll-free directory assistance caller. In 1999, AT&T applied for permission to discontinue this service[2] but it remains active.

Directory assistance data sources[edit]

The services of 4-1-1 queries is often outsourced to a call centre that specializes in that function. Historically, when a single carrier provided most of the telephony services for a region, the data used to satisfy the search could come exclusively from that carrier's subscriber rolls. Today, when the market is fragmented amongst many carriers, the data must be aggregated by a data aggregator specializing in directory listings, such as LSSi. The data aggregator distributes the data to the 4-1-1 services either on a "live" basis, actually servicing each query, or by periodically transferring large swaths of listings to the call center's systems for local searching or for online directory assistance searching at 411 directory assistance.

The data aggregator collects the data from the rolls of many telecommunication carriers. Some carriers such as Vonage do not send their customer rolls to the aggregator. Their customers can get their listings in the directory assistance database using a free service such as

Companies specializing in free directory assistance[edit]

Recently private companies have entered the directory assistance market by offering free directory assistance. Customers often must listen to an advertisement prior to receiving directory services.[3] In Canada, free Local and National Directory Assistance service for business and residential listings is available online by 411 Directory Assistance Canada.[4]

United Kingdom[edit]

The BT foreign directory assistance centre in Grimsby (1996)

In the United Kingdom, directory assistance is called directory enquiries. The service is provided by a variety of different companies, with a variety of call charges, each company reached by dialling a six-digit number beginning with 118. These companies supply information from the Operator Services Information System (OSIS), which is run by Directory Solutions, a division of BT Wholesale. OSIS accepts updates from telecoms providers seven days a week, and supplies that information to the enquiry companies six days a week.[5] There are currently over 200 providers. Three of these, 118 500 (BT), 118 888 (Conduit) and 118 118 (The Number), have over 90% of the market, mostly due to heavy advertising.[citation needed]

Directory enquiries used to be reached by dialling 192 (domestic numbers) or 153 (foreign), with the service supplied by the telephone company providing the fixed or mobile service to the calling telephone. These numbers were switched off on 24 August 2003 following the introduction of competition to directory enquiries.

A number offering a directory enquiries service allowing people to request to be put through to a mobile phone number was established in June 2009.[6] 118 800 proved to be controversial, however, when it was revealed that it was making available 15 million mobile numbers that it had bought from market researchers.[7] Its website was suspended[8] within weeks of its launch so that the company could re-engineer the site to enable the large number of ex-directory requests to be handled more efficiently.[7] As of 2016 the site remains non-functional.


The pricing structure for UK directory enquiries is very complex. Some services are fixed fee, some are per minute and some are a combination of the two. Each number is allocated to a code from dq1 to dq153 and these are shown in BT's pricing table section 2, part 15.[9] Having found the "dq" code, it is then necessary to refer to part 19 to find the cost.[10]


Some services donate part of their income to charities, such as animal welfare and football clubs.[11]


In mainland China, (area code) 114 is dialed for directory assistance in that area code.[12]


In Ethiopia, 8123 is dialed for directory assistance. The service can also be accessed through the site Afalagi's website


In Israel, 144 or 1344 is dialed for directory assistance. The service can also be accessed online through Bezeq's website


In the Philippines, 187 is dialed for PLDT[13] and Digitel subscribers.


In Taiwan, directory assistance is available by dialing 105 from mobile phones, or by dialing 104 from landline phones.

See also[edit]


  1. ^ 411 Directory Assistance Archived 2 June 2015 at the Wayback Machine. 411 Directory Assistance
  2. ^ *AT&T Inc. (16 November 1999). "Discontinuance - AT&T Toll-Free Directory Assistance Service - 1-800-555-1212". FCC Public Notices. Federal Communications Commission. Retrieved 2007-12-28. 
  3. ^ Bernstein, Fred A. (9 March 2006). "The 411 on Directory Assistance". The New York Times. Retrieved 1 May 2010. 
  4. ^ 411 Directory Assistance Canada 411 Directory Assistance Canada
  5. ^ "BT Wholesale Directory Solutions - About Us". British Telecom. Archived from the original on 30 November 2009. Retrieved 13 January 2010. 
  6. ^ "118 800 To Connect UK To Millions Of Mobile Numbers". Real Wire. 9 June 2009. Retrieved 19 July 2009. 
  7. ^ a b Osborne, Hilary (13 July 2009). "Mobile phone directory suspended". London: The Guardian. Retrieved 14 July 2009. 
  8. ^ "118800 Mobile Enquiry Service Temporarily Suspended'". PR Log. 29 July 2009. 
  9. ^ "BT Price List – Section 2, Part 15". Retrieved 2016-06-07. 
  10. ^ "BT Price List – Part 19: Calls to Directory Enquiry 118 Services". Retrieved 2016-06-07. 
  11. ^ "118 Numbers". Retrieved 2016-06-07. 
  12. ^ "号码百事通" (in Chinese). China Telecom. Retrieved 14 July 2013. 
  13. ^ "Contact Us". Retrieved 2016-06-07. 

External links[edit]