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4-1-1 is the telephone number for local directory assistance in the United States and Canada. One exception is the Pacific Northwest, which used 1-1-3 until the mid-1980s. Until the early 1980s, 4-1-1 calls were free in most states.
4-1-1 has also been used for long-distance directory assistance in most areas in the United States and all of Canada. The traditional long-distance directory assistance number is 1-area code-555-1212.
4-1-1 is also commonly referred to as "D.A.", "Directory Assistance", or "Information". Prior to the introduction of Direct Distance Dialing (DDD) in the 1950s, which required dialing "1" to initiate a DDD call, the number for "Information" was 1-1-3 ("Repair" was 1-1-4). All existing local numbers beginning with 1 had to be changed, so "Information" and "Repair" (and others) changed to 411 and 611, respectively. Approximately 6 billion calls are made to 4-1-1 within the United States every year.
Outside North America, "1-1-N" numbers are still in use, for these and other services. In most European countries "1-1-N" numbers are related to emergency services and 112 is the European Unified Emergency Number.
Directory assistance data 
The services of directory assistance queries is often outsourced to a call centre who 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 exclusively come for that carriers 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.
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 assiatance database using a free service such as ListYourself.net.
Landline telephone directory assistance 
4-1-1 landline service has been historically provided by local telephone companies, including those of the former Bell System or subsequent Regional Bell Operating Companies (RBOCs). Telephone carriers since that time may provide the 4-1-1 calls to the customer free of charge and use ad supported or a customer retention model
Since the 1984 Bell System divestiture, the RBOCs in the United States have priced 4-1-1 use higher to an average of $1.25 USD per call, compared to $0.50 CAD in most of Canada, providing opportunities for competing services in the United States, such as ad-sponsored 1-800-FREE-411.
Wireless telephone directory 
In addition to the local and long distance directory services, there is also consumer-choice and privacy-protected "Wireless 411 Service". As specified by the industry, the service will give consumers the choice of including their wireless phone numbers in voice 411. Consumers who choose to opt in will not have their information disclosed for print, online directories, lists, or telemarketing firms. The service will allow any landline or wireless phone user to call 4-1-1 and be connected to the wireless listing of a person who has chosen to participate in the service. Carriers who make up the industry LLC creating the service include Alltel (now absorbed by Verizon Wireless), AT&T, Sprint Nextel and T-Mobile.
See also 
- Directory assistance
- Bing Mobile
- Speech recognition
- Tellme Networks
Further reading 
- Recent survey from Tellme Networks, Inc. about 411 usage
- The Kelsey Group report on wireless voice search (10/2006)