Integrated Services Digital Network Primary Rate Interface (ISDN PRI) is a digital voice service that provides high-volume access to the public switched telephone network (PSTN). ISDN PRI provides 23 digital channels over one transport line (a 24th channel carries signaling information). ISDN PRI consolidates its 23 voice channels on one 1.544 Mbps transport line into a PBX or computer network.

You can use one D channel to control multiple ISDN PRI lines, freeing the 24th channel on additional ISDN PRI circuits to increase capacity. Backup D channels provide a contingency for inoperable D channels. If a failure occurs, a predetermined D channel on another ISDN PRI connection automatically takes over call control signaling for your calls.

How it works

ISDN PRI is a digital connection for voice between your PBX and the AT&T public switched telephone network (PSTN).

Features and Benefits

Integrated Services Digital Network Primary Rate Interface (ISDN PRI) gives you these features:

  • Digital Connection to Public Switched Telephone Network—ISDN PRI is a standard protocol that operates both in the AT&T digital public switched telephone network and in most PBX and computer networking hardware.
  • Digital Streamlining—ISDN PRI offers a single digital connection at a lower total cost of ownership than the comparable analog connections that would be otherwise required. Moreover, digital signals provide a better-quality voice transmission over copper facilities. With the use of Call-by-Call technology (dynamic call allocation), the net gain of implementing ISDN PRI may allow you to actually reduce the number of trunks you have today.
  • Advanced Calling Features—The digital connection between your PBX and the AT&T central office provides you with inherent central office features (Caller ID is one example). Caller ID display equipment is required for Caller ID service.
  • Multiple Types of Information Through One Trunk—ISDN PRI is a proven communication protocol throughout telecommunications networks. The majority of digital PBX equipment available today is ISDN PRI compatible. Provided your equipment can break down information into digital signals, ISDN throughout the AT&T infrastructure can carry it.



Details/SpeedMonthly Recurring ChargeNon-Recurring Charge
PRI-ISDN – 1.5Mbps$649.59$0.00
DID Telephone Number$0.21$0.00
Calling Name Delivery (per PRI)$102.50$0.00

Regulatory Fees

  • End User Common Line (EUCL)/Access Recovery Charge (ARC) Fee = $52.55 per PRI
  • Federal Universal Service Fund (FUSF) = $16.30 per PRI
  • 911 Fee = $1.50 per B-Channel. (Note: Some entities may be exempt)
  • Telecommunications Relay Service = $.55 per PRI
  • Georgia Universal Access Fee = 4.9% of all Intrastate billing
  • Federal and State Taxes may apply based on Tax exemption status
  • Fess subject to change based on FCC filings

Pricing Notes

  • Pricing provided for a flat-rate PRI includes: T1 local channel, voice/data interface, and 23 B Channels. Telephone numbers are charged separately based on quantity required. Select optional features may require an additional charge. Long distance services are not included and will be charged separately.
  • Service Availability validation is required.
  • Only available in AT&T Service Area.

Product Specific Terms and Conditions

  • Withdrawal of Service. AT&T reserves the right to withdraw a Service upon reasonable Notice. Service withdrawal with 12 months notice and Service Component withdrawal with 120 calendar days notice.

AT&T Service Guide Link for Additional Product Information