PRI: Primary Rate Service PRS

Primary Rate Service

Digital Connectivity For Your Evolving Voice, Video And Data Transport Needs

Businesses are built on connecting with customers and suppliers, and Primary Rate Service employs an established, worldwide telecommunication standard to foster powerful global connections. PRS is technology for today and tomorrow. It links your PBX to CenturyLinks advanced central office systems, supporting digital connectivity, data file transfer, voice calls, fax transmission and video traffic. Key applications include:

  • Voice and data integration.
  • Private branch exchange (PBX).
  • Local area network (LAN) interconnection.
  • Video conferencing.
  • Virtual office.
  • Backbone LAN access.
  • Image transfer.
  • Business continuation and disaster recovery.


PRS is a switched-trunk service based on Integrated Services Digital Network (ISDN) that integrates voice, video and data applications simultaneously over the same DS-1 facility. It combines 23 circuitswitched voice and data channels offering bandwidth up to 1.544 Mbps with one D channel used for call setup, signaling and network control. This seamless communications system speeds and smoothes the flow of information without the expense of dedicated lines, modems and special cabling. As your needs grow, the functionality of PRS will provide digital connectivity that is feature-rich, flexible and widely available.


  • Voice and data transmissions employ crystal-clear channels.
  • Any channel can carry any type of connection, eliminating the need for single-purpose trunks such as direct outward dial (DOD), dedicated video and data private lines.
  • Features Caller ID, Direct Inward Dialing (DID) and rapid call setup.
  • Regional pricing options available for remote locations.
  • Channel bonding used for added cost efficiency, rapid scalability and added control and flexibility.
  • Functionality across standard analog four-wire and fiber optic circuits employs technology that is both widely deployed and cost effective.


  • Connectivity—Employs an established telecommunication standard that allows large data files to be digitally transferred locally or globally.
  • Efficiency—Supports simultaneous Internet access, data file transfer, voice calls, fax transmission and video traffic.
  • Fast data speeds—Bond channels to provide higher data speeds in increments of 64 Kbps. ISDN provides a clear, crisp communications connection where noise and bit errors are not a factor. Lines and host computers get fast, reliable backup.
  • Service—Offers industry-leading, Tier II technical support including network monitoring (four-hour service window) and 24/7 technical support.
  • Flexible capacity—Allocate additional channels to an application in any multiple of 64 Kbps.
  • Customer flexibility—Bandwidth-on-demand provides exceptional flexibility with the functionality of multiple communication circuits at a comparable price.
  • Borderless communications—Share all types of information with virtually anyone, anytime, anywhere.

How It Works

The DS-1 based service uses the 23 B channels to carry all user data (voice, data and video) and one D channel to carry call supervisory information such as call setup, Caller ID, routing information and channel designations. Because of the D channels control, the B channels are free to carry all information bits. This type of signaling, in which the information is sent over a band separate from the actual call, is known as out-of-band signaling. PRS combines the features of three types of digital switching: circuit switching, packet switching (transmitting data in individual packets) and common channel switching using Signaling System 7 (SS7) to vary the means of transmission as necessary.

Why Buy From CenturyLink?

  • The Spirit of Service® ensures you receive exceptional service and support from a communications partner that works with you to develop the right solutions for your business.
  • CenturyLink provides 24/7 customer care.
  • CenturyLink is a proven communications provider with years of experience.

Other Products Available From CenturyLink

In addition to Primary Rate Service, CenturyLink has an array of products to meet your needs including:

  • Digital Switched Service
  • Long Distance
  • CenturyLink Private Line
  • Direct Inward Dial
  • Toll Free
  • Conferencing
  • Interaction Routing
  • CenturyLink IQ Networking®

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