What is "NEBS Level 3"?

"NEBS Level 3" is a term from Bellcore special report, SR-3580.  This report details 3 distinct functional levels of NEBS compliance based on GR-63-CORE and GR-1089-CORE.  The levels allow a wide range of NEBS requirements to be applied to equipment based on application and network impact.

"NEBS Level 1" means that people and equipment hazards and network degradation are minimized.  NEBS Level 1 addresses the personnel and equipment safety requirements of GR-63-CORE and GR-1089-CORE.  This is useful for getting prototypes into a lab trial.  It's also a requirement that is imposed on Competitive Local Exchange Carriers (CLECs) in order for them to deploy equipment into an RBOC's network.  This level doesn't address operability, this is addressed in Levels 2 and 3.

"NEBS Level 2" addresses equipment operability, but in a controlled environment.  For example, equipment could be used in a data center, however, if the equipment performs non-critical operations it could be used under environmental extremes.  Note that this level is very rarely used because it is ambiguous.

"NEBS Level 3" means the equipment is in the network for the long haul.  We're talking about Carrier Class with this stringent level.  The equipment will operate under the environmental extremes found in a central office.  In a nutshell, the equipment meets all of the requirements of GR-63-CORE and GR-1089-CORE.

Telcordia has created a special NEBS page to their SuperStore providing customers with more info on the NEBS documents. Check out Telcordia NEBS Page


  1. Verizon does not follow SR-3580.  They use their own NEBS checklist,  NEBS Compliance Clarification Document, that details what they believe are important to their network's integrity.
  2. SBC uses 2 levels as detailed in their NEBS checklist TP76200MP.
  3. A combined Telecommunications Carrier Group Checklist can be found here TCG Checklist.