Wholesale: Products & Services

Asynchronous Transfer Mode (ATM) Service - V18.0

NOTE: Asynchronous Transfer Mode (ATM) Service is grandfathered in all states effective October 15, 2018 and is no longer available as a new service. This product will be eliminated as of March 1, 2019.

History Log

Product Description

Asynchronous Transfer Mode (ATM) Service uses high speed ATM networking technology to bundle information into fixed segments called cells. ATM is based on industry standards governed by the ATM Forum. The ATM protocol is designed to support many different business applications within an enterprise network, treating each business application based on its bandwidth and Quality of Service (QoS) needs. ATM Service supports speeds from 1.544 Megabits (Mbps) to 622 Mbps.

Asynchronous Transfer Mode (ATM) Service requires the use of Customer Premises Equipment (CPE) that puts customer data into cells suitable for transmission over the CenturyLink™ ATM network. The CPE is purchased separately from ATM service and must conform to industry standards.

Product Diagram



Asynchronous Transfer Mode (ATM) Service is available where facilities exist throughout CenturyLink QC.

CenturyLink's Network Disclosure 400, provides information on availability of ATM by CenturyLink wire center.

Terms and Conditions

Asynchronous Transfer Mode (ATM) Service requests requires a Funding Approval for Digital Signal Level 3 (DS3) and above port speeds.

Customers wanting a coterminous contract will need to contact their CenturyLink Sales Executive to obtain a contract identification number. The contract identification number must be noted in the Variable Term Agreement (VTA) field of the ASR or under the contract section of the IR ATM Service Request Form. If contract terms are requested and no contract identification number is provided on the ASR the ASR number will be used as a contract identification number for the request. Contract terms must be noted in the VTA field and the remark field of the ASR when no contract identification number is being provided.

For more information on Terms and Conditions, contact Account Team / Sales Executives and Service Managers.

Terms and Conditions

Technical characteristics, including Network Channel /Network Channel Interface (NC/NCI™) codes, are described in Technical Publication, Asynchronous Transfer Mode (ATM), 77378.


Rate Structure

Recurring charges are comprised of the following rate elements:

  • Bandwidth Increments per ATM quality of service levels:
    • Available Bit Rate (ABR)
    • Constant Bit Rate (CBR)
    • Variable Bit Rate-real time (VBR-rt)
    • Variable Bit Rate-non-real time (VBR-nrt)
    • Unspecified Bit Rate (UBR)
  • Cell Burst Size
  • Central Office Connecting Channel (COCC)
  • Digital Signal Level 1 (DS1) ATM Access Link
  • Inverse Multiplexing over ATM (IMA Access Link) number of DS1 (NxDS1) up to 8 DS1s
  • Optical Access Link (OAL)
  • Port
  • Protected Optical Access Link (OAL) with Diversity (Diversity is optional)
  • Protected Stand-Alone Optical Access Link (SAOAL)
  • Transport Mileage - (applies to only Independent Telephone company locations and non disclosed ATM locations) � Refer to Private Line Transport Tariffs for DS1and DS3 and CenturyLink Corporation Rate and Services Schedule No. 1 (QC RSS No. 1) for Optical Carrier Level 3 (OC3) and, Optical Carrier Level 12 (OC12) pricing.

Nonrecurring charges are comprised of the following rate elements:

  • Central Office Connecting Channel (COCC)
  • DS1 ATM Access Link
  • Inverse Multiplexing over ATM (IMA) Access Link (NxDS1, up to 8 DS1s)
  • Optical Access Link (OAL)
  • Port
  • Protected Optical Access Link (OAL) with Diversity (Diversity is optional)
  • Protected Stand Alone Optical Acces Link(SAOAL) with Diversity (Diversity is optional)
  • Stand-Alone Optical Access Link (SAOAL)
  • Subsequent Order Charge for IMA Access Link
  • Subsequent Order Charge for IMA Port
  • Subsequent Service Order Charge for VPC/VCC
  • Transport Mileage (applies to only Independent Telephone Company and non-disclosed ATM locations) - Refer to Private Line Transport Service Tariff for DS1, DS3, OC3, OC12 pricing.
  • VCC (Virtual Channel Connection)/VPC (Virtual Path Connection)

Additional rate structure information can be found in the QC RSS No. 1, tariff, the state specific tariff, or your Interconnection Agreement.


Rates are available in Exhibit A, QC RSS No. 1, , or state specific tariff.

Existing Interstate Fixed Period Rate Plans which have expired, or are within three months of the expiration date, have the ability to subscribe to a new one year or greater Fixed Period Rate Plan and receive a discount on the current Monthly Recurring Charges in the Fixed Period Service Rate Plan and a reduced Termination Liability Assessment percent. Contact your CenturyLink Sales Manager for additional information.

Additional information on expiring Interstate Fixed Rate Plans and their associated discounts is available in QC RSS No. 1 Tariffs/Catalogs/Price Lists.

Tariffs, Rates and Services Schedule (RSS), Regulations and Policies

Tariffs, RSS, regulations and policies are located in the QC RSS No. 1 or state specific Tariffs/Catalogs/Price Lists.

Optional Features

CenturyLink ATM features include:

Inverse Multiplexing over ATM (IMA): ATM IMA service offers bandwidth options between DS1 (1.544Mbps) and DS3 (45Mbps) levels. IMA utilizes 2 to 8 DS1s and bundles them together to create a solid bandwidth increment from 3Mbps to 12Mbps.

IMA distributes traffic evenly across multiple links to create a single high capacity virtual link that fills the gap for intermediate DS1-DS3 bandwidth requirements, offering an alternative in fiber or DS3 depleted areas and providing a natural progression for customer access in approximately the 3-12 Mbps bandwidth range. QoS levels available with IMA include CBR, VBR-nrt, and UBR.

Inverse Multiplexing over ATM_IMA_diagram

Frame Relay Service (FRS) to ATM Service Interworking - Interworking PVC (IPVC): ATM IPVC allows FRS and ATM customers to communicate with each other. IPVC will perform mapping from/to the FRS dedicated connection (PVC) to/from the ATM dedicated connection (VCC) utilizing UBR ATM QoS level. IPVC provides flexibility and the customer can use the service (FRS or ATM) best suited for its specific application needs. It enables a migration path for the large number of FRS customer to ATM. IPVC provides customers with the opportunity to balance high bandwidth host or headquarter site application needs (ATM IMA/DS3/OC3/OC12) with less expensive FRS access speeds (DS0/DS1/fractional FR port), Customers can implement ATM at new sites as needed at their own pace and protect their existing service investment.

Frame Relay to ATM Interworking_diagram


Features Benefits
Quality of Service (QoS) Levels
  • Five service levels available to support different business application requirements - CBR, VBR-rt, VBR-nrt, and UBR
  • Ensures that the most critical traffic receives the greatest resources and the best service
  • Supports multiple branch offices to service multiple business applications within an enterprise network
Cost Effective
  • Equipment, network, operations, and administration costs lowered by consolidating different applications on one network
  • Logical connections over a single physical access link and port connection for communicating among multiple end user locations
  • End-to-end integrator for transport, equipment, and network management
  • Speeds of DS1, NxDS1, DS3, OC3 and OC12 offered to meet customer communications requirements
  • Pay only for the amount of bandwidth required for specific business applications
  • Seamless internetworking with Frame Relay, CenturyLink Commercial Broadband Services, Ethernet and IP services.
Proactive network Monitoring and Network Maintenance
  • Excellent network reliability and availability, with inherent redundancy and security.
  • 24/7/365
  • Redundant, world-class Network Operations Centers and systems


Applications suitable for ATM Service include:

  • Voice and video
  • Packetized voice and video
  • Systems Network Architecture (SNA)
  • WAN/VPN connectivity
  • Web hosting
  • E-commerce
  • Client-server (terminal-host) data
  • LAN interconnection
  • LAN emulation
  • Remote access
  • File transfer
  • Internet/intranet/extranet access
    • E-mail messaging
    • Text imaging
    • Forms processing


Product Prerequisites

If you are an Interexchange Carrier (IXC), Internet & Data (ISP) or Wireless Service Provider (WSP) and have questions regarding your contract with CenturyLink, contact your Account Team / Sales Executives and Service Managers for more information.


General pre-ordering activities for ATM can be found in Customer Electronic Maintenance and Repair-Maintenance Ticketing Gateway (CEMR-MTG)

  • Customer Service Record (CSR)
  • Service Availability
  • Validate Address
  • Validate Connecting Facility Assignment (CFA)

Customer Service Record (CSR) can be obtained through emailing Wireless.PLT@CenturyLink.com a request to CenturyLink. The following information is needed to process your request:

  • Email address
  • End-Users account telephone number
  • Fax Number
  • Proof of agency authorization

Contract Process: Interstate Asynchronous Transfer Mode (ATM) Service must be purchased under contract.


ATM is service requests can be issued by submitting ASR or IR ATM Service Request Form.

Your CenturyLink Account Manager/Service Manager will complete the IR ATM Service Request form with your assistance, contact your Account Team / Sales Executives and Service Managers.

ATM service requests can be submitted by using the following Access Service Ordering Guidelines (ASOG) form:

ASOG form New Connect Change Disconnect*
Access Service Request (ASR) X X X
ASR Administration Information X X X
ASR Priloc End-User Special Access X X X
Service Address Location Info-Priloc X X X
ASR Secloc End User Special Access X X X
Virtual Connection Form X X X
Order Tracking Information X X X

*ECCKT and Customer Name needs to be included on a disconnect

Field entry requirements are described in the Access Service Request (ASR) Forms.

A Design Layout Record (DLR) requested on the IR ATM form.

For more information on ordering ATM contact your Account Team / Sales Executives and Service Managers.

Provisioning and Installation

Firm Order Confirmation (FOC) intervals are found in the Service Interval Guide (SIG).

For more information on provisioning and installation contact your Account Team / Sales Executives and Service Managers.

Maintenance and Repair

For repair, contact the ATM repair service by calling 800 227-2218.


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


No training is available for Asynchronous Transfer Mode (ATM) Service, however to view other CenturyLink courses click on Course Catalog.


CenturyLink contact information is located in Wholesale Customer Contacts.

CenturyLink Wholesale Team Tool (CWTT) is a means to identify your account contacts within CenturyLink.

Frequently Asked Questions (FAQs)

1. What is ATM technology?
ATM is a high speed networking technology based on two very simple concepts-network conformity and QoS. Information (data, video, Internet and voice) transferred across an ATM network is carried in 53-byte chunks known as cells. The fixed length cell enables ATM to transfer information faster than Frame Relay or Internet Protocol (IP) with the highest degree of data integrity and the lowest degree of latency of any existing networking technology. A 53-byte cell is comprised of 48 bytes of payload (user information) and a 5-byte header. The 5-byte header enables all addressing and QoS information to be tagged at the front of a cell and allows the payload (user information) to be switched, instead of routed, without delay and according to priority. Using a uniform cell structure allows all information to travel the network at a known interval. By putting information from different business applications into cells, the cells can share the same network and still be treated in the same manner without latency or loss of integrity.

2. What is the difference between Frame Relay and ATM?
Frame Relay has a variable length packet (frame) whose size depends upon the amount of information transmitted and ATM uses a fixed length packet (a 53-byte cell). The switching of cells enables information to be switched very quickly in hardware and has the ability to intermingle data, video, Internet and voice without compromising the unique need of each application.

3. How do I find out where ATM is available?
ATM network disclosure is available at: http://www.centurylink.com/disclosures/netdisclosure400/index.html

4. What are PPD and EPD?
PPD stands for Partial Packet Discard and EPD stands for Early Packet Discard. PPD and EPD are the commonly used industry terminology for intelligent frame discard capability as an optional congestion recovery procedure. EPD is a packet discard mechanism congestion control technique that discards every cell from an ATM Adaptation Layer 5 (AAL5) Packet Data Unit (PDU) when an ATM device buffer overflows. It prevents cells from entering the buffer, reserving remaining buffer capacity for cells from packets already admitted. PPD occurs when a device drops one or more cells of the same AAL5 PDU. It discards all remaining cells of an AAL5 PDU except the last one. This mechanism avoids transmitting cells across the network the AA5 receiver would fail to reassemble.

5. What speeds and ATM service categories are available for ATM to DIA?
ATM to DIA PVCs are available only on DS3 and above ports using CBR service category.

6. What is the difference between a VPC and VCC?
A Virtual Path Connection (VPC) can carry multiple Virtual Channel Connections (VCCs). It is our customer's responsibility to provision VCCs within a VPC. The sum of all the VCCs needs to conform to the traffic parameters that the customer signed up for on a VPC. Think of it as a phone number. If another carrier comes to Denver and buys 303-222 phone numbers from us (VPC), then we would route all the phone calls btw/ 303-222-0000 and 303-222-9999 to that carrier. The carrier will assign the individual numbers within that range themselves (VCCs). CenturyLink will just treat them as a "block of numbers" that is carried from one end-point to the other.

7. A customer bought a VPC and asked us to manage the VCCs on their ATM network. Is that possible?
When you set up a VPC across the ATM network, the switch does not have the ability to look into the individual VCCs within that VPC. The customer buys a VPC with the intent of managing the VCCs within that VPC. The customer also selects the bandwidth and the Class of Service for the aggregate of all the VCCs in the VPC. The customer is responsible for managing to the aforementioned parameters. That is the whole reason for the VPCs existence-flexibility and customer control. If the customer does not want that, they need to convert to VCCs (PVCs) and CenturyLink will manage it for them.

8. Can a customer oversubscribe an ATM HOST? For example, I have a DS-3 ATM with 45 Megs of Internet access at a host location in AZ, I have two other remote locations in AZ with 9 Megs of ATM pointing back to the host location in AZ with the 45 Megs of Internet. Please clarify CenturyLink's over subscription policy.
The answer depends on the QoS, the amount of traffic and the number of users. You can't get more than 45Mbps at one time through a 45Mbps port. This is not a case of oversubscription, but rather bursting. Please refer to the CenturyLink ATM Technical Publication 77378 regarding the bursting policy.

9. Does a customer need fiber-optic cabling to their business to subscribe to CenturyLink ATM Service?
No, ATM Service supports both optical (OCn) and electrical interfaces (T1, DS3)

Last Update: October 15, 2018

NC/NCI™ is a Trademark of Telcordia Technologies, Inc