Wholesale: Products & Services

Directory Assistance (DA) - Interexchange Carriers (IXC) - V12.0

History Log

Product Description

Directory Assistance (DA) Service provides subscriber listing information to your customer when the end-user dials 1+ NPA 555-1212. The listing information is comprised of name, telephone number, address and/or ZIP code. Listing information can be obtained by a name, telephone number or type of business, (i.e., florist, plumber, etc). DA Service provides Directory Access Service to DA locations, use of DA access equipment and agents to provide listing information on a regional and national basis.

A maximum of two requests for listing information shall be accepted per call to the DA agent. A telephone number that is not listed in DA records is not available to your end-user. Non-published subscriber telephone number information is not provided.

Two primary types of DA Service are available:

  • Regional/Local (RDA)
  • National Directory Assistance (NDA) (with or without call completion link)


Regional/Local DA Service or Regional Directory Assistance (RDA), obtains listing information within CenturyLink QC on a per Numbering Plan Area (NPA) specific basis.


National DA (NDA) Service obtains listing information for any NPA in the United States, Canada and Puerto Rico.

Call Branding

The DA services include call branding. "Call Branding" means announcing CenturyLink's name, your name, or a generic name on the front end and/or back end of the DA calls.

You have the option of choosing what type of branding announcement you wish to have recorded and played at the beginning and/or end of your end-user's calls to CenturyLink DA.

Front End Call Branding announces CenturyLink's name, your company's name, or a generic name at the beginning of the call.

Back End Call Branding announces CenturyLink's name, your company's name or a generic name at the conclusion of the call.

Three types of DA Call Branding are available. Calls may be branded with CenturyLink's brand, generic call branding and customized call branding as follows:

  • CenturyLink Branding - announces CenturyLink's name
  • Generic Call Branding - announces no name (e.g., Directory Assistance (front end) and Thank you for using your local telephone company (back end))
  • Customized Call Branding - announces your name (e.g., ABC Telephone Company - Directory Assistance (front end) and Thank you for using ABC Telephone Company (back end)


Regional Directory Assistance (RDA), and NDA are available to IXCs where facilities exist nationwide. Search by 'type of business' or 'business category' search is not available when you are connected to a 5E (Lucent) switch that is located in CenturyLink's Eastern Region (IA, MN, ND, NE & SD).

Terms and Conditions

CenturyLink will perform DA Services in accordance with operating methods, practices and standards in effect for all end-users. CenturyLink will respond to your end-user calls to CenturyLink DA Services using the same call handling priority used to respond to CenturyLink end-user calls. Calls to CenturyLink DA Services are handled on a first come, first served basis.

Directory Assistance (DA) Service for Disabled End-users

CenturyLink considers the relationship between you and your end-users a private and confidential matter. CenturyLink provides CenturyLink DA services to you, regardless of the end-user, and will charge you for those services according to your agreement.

Technical Publications

Technical characteristics, including Network Channel /Network Channel Interface (NC/NCI™) codes, are described in Technical Publication, CenturyLink Switched Access Service - Network Channel (NC) and Network Channel Interface (NCI) Codes Combinations, 77203.


Tariffs, regulations and policies are located in the CenturyLink Operating Companies Tariff F.C.C. No. 11 Tariffs/Catalogs/Price Lists.

Optional Features

National Directory Assistance (NDA) with Call Completion Link (CCL)

The CCL feature returns the end-user to your switch so that they can be connected to the requested telephone number over your network. This feature is only available for NDA services.

Call Completion Link (CCL) is available with or without Release to Pivot (RTP) capability. SS7 out of band signaling is required. This service must be designed in accordance with Telcordia™ Technical Reference GR-3016-CORE and Technical Publication, CenturyLink COMMON CHANNEL SIGNALING (CCS) NETWORK INTERFACE SPECIFICATION(ADDENDUM TO GR-905 AND GR-954), 77342


Features Benefits
Daily updates made to a database of more than 100 million listings
  • Gives end-users access to the most accurate, comprehensive information
  • End-users dial 1+NPA-555-1212
  • Uses the same dialing pattern that is familiar to end-users
  • Operators can search by name/city, name/state or by telephone number and in most cases by business type.
  • Does not require extensive information from end-users before initiating search
  • Provides telephone numbers, addresses, and/or zip codes, where available, for anyone in any of the 50 states.
  • Offers a single source of information for telephone subscribers nationwide
  • Front-end branding is available for all DA services and back-end branding is available
  • Reinforces the carrier's relationship with their end-users
  • Calls answered more than 90% of the time within 10 seconds
  • Provides a fast, but personal response to end-user inquiries
  • 24/7 assistance
  • Ensures reliable service and support
  • Implementation

    Product Prerequisites

    Interexchange Carriers that plan to originate or terminate intrastate or interstate traffic must determine if they need to apply to the local Public Utilities Commission or Corporation Commission to obtain a Certificate of Public Convenience and Necessity (CPCN). IXC must obtain an ACNA (Access Customer Name Abbreviation) and CIC (Carrier Identification Code) from Telcordia, and set up an account with the CenturyLink Wholesale Center for Customer Service. You must also submit a Letter of Intent to the CenturyLink Sales Executive or Service Manager on your company's letterhead.

    Customized Call Branding for DA will entail recording and setup of a brand message.

    You must complete the Operator Services/Directory Assistance Questionnaire for Interexchange Carriers (IXCs). If you have questions regarding completion of the questionnaire, please contact your CenturyLink Service Manager. CenturyLink will process your request to access CenturyLink's Operator Services based on your completed questionnaire(s).


    Interexchange Carriers must do the following to obtain DA Service:

    • Order a one-way or 2-way Operator Trunks with FGD signaling/protocol trunk(s) from their originating Point of Presence (POP) to the appropriate CenturyLink Traffic Operator Position System (TOPS) switch for each type of service that is requested. (Applies to RDA, NDA and NDA with CCL).
    • Order a separate trunk group for each NPA, when required by CenturyLink. (RDA only)
    • Assume responsibility for all contacts and arrangements concerning the provision and maintenance of, and the billing and collecting of charges for DA service furnished to their end users.
    • Provide an estimate to CenturyLink of the amount of DA traffic that will be generated on a per month basis for a twelve (12) -month period.

    Mutually agree with CenturyLink on customized branding information.


    Once the Prerequisites and Pre-Ordering tasks have been completed the CenturyLink Service Manager will work with you to begin the Implementation process.

    CenturyLink DA Service is ordered by completing an Access Service Request (ASR) form and the Operator Services/Directory Assistance Questionnaire for Interexchange Carriers (IXCs.) You are required to order the trunk group from a point of presence in the switch to be mutually agreed upon by you and CenturyLink OIS (Operator and Information Services) personnel. No other type of traffic may be carried on this trunk group.

    The following trunks must be ordered for the service indicated:

    • RDA - one-way multi-frequency (MF) trunk group per NPA
    • NDA without call completion - one-way SS7 terminating trunk group
    • NDA with call completion/release link trunking (RLT) - 2-way SS7 trunk group
    • NDA with call completion/hairpin - Originating one-way SS7 trunk group and Terminating one-way SS7 trunk group (note: 2 ASRs are required)

    The ASR for most Directory Assistance Services carries a "SPEC" code which is unique to the type of Directory Assistance Services. There is no spec code needed for RDA. For NDA, you will populate the "SPEC" code with NATLDA. Each ASR should also contain the Traffic Type code. The Traffic Type code is dependent on the type of services you order. Below is a table of the ASOG Traffic Type codes and a brief description:

    DA Directory Assistance
    DC Directory Assistance Call Completion Service
    ND National Directory Assistance

    NOTE 1: "OP", "ID", "DA", "DD,", "50", "80", "90", "PO", "C0", "C1" and "IO" are all types of originating traffic. If the quantity ordered is unique for only one type of originating traffic, the customer will utilize one of these codes. However, if the quantity ordered is a mixture of different originating traffic types, the customer will use "OT".

    The following table contains key elements of the Directory Assistance Services ASR entries. These entries should be discussed with your service manager prior to placing your order.

    Following are necessary ASR entries required to provision this service:

    Regional Directory Assistance (RDA) ASR Entries

    Field Enter
    SPEC Leave field blank
    SECLOC TBD based on switch chosen
    CSPC TBD based on switch chosen
    Traffic Type code See table above
    NC Code SD-D

    National Directory Assistance (NDA) ASR Entries

    Field Enter
    SECLOC TBD based on switch chosen
    CSPC TBD based on switch chosen
    Traffic Type code See table above
    NC Code SHSA

    National Directory Assistance (NDA) with CCL using Release to Pivot or Release Link Trunking

    ASR Entries

    Field Enter
    SECLOC TBD based on switch chosen
    CSPC TBD based on switch chosen
    Traffic Type code See table above
    NC Code SHSA

    National Directory Assistance (NDA) with CCL using Hairpin Solution

    ASR Entries

    Note: 2 ASRs are required for this service for originating and terminating.

    Field Enter
    SECLOC TBD based on switch chosen
    CSPC TBD based on switch chosen
    Traffic Type code See table above
    NC Code SHSA

    For any subsequent order activity (i.e., add, change or delete an existing service) you must complete the Operator Services/Directory Assistance Questionnaire for Interexchange Carriers (IXCs.

    The Interexchange Operator Services/Directory Assistance Services Disconnect request form is used to discontinue DA Service.

    Maintenance and Repair

    If you encounter problems with the service, contact your CenturyLink Service Manager.


    Carrier Access Billing System (CABS) billing is described in Billing Information - Carrier Access Billing System (CABS).


    View additional CenturyLink courses in the Course Catalog.


    CenturyLink contact information for Interexchange Carriers is located in Interexchange Carrier Customer Contact.

    Frequently Asked Questions (FAQs)

    This section is being compiled based on your feedback

    Last Update: January 30, 2017

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