---

• CCITT Rec. M.20 (11/1988) – MAINTENANCE PHILOSOPHY FOR TELECOMMUNICATIONS NETWORKS
• 1 General
• 2 Maintenance objectives
  • 2.1 Purpose
  • 2.2 Economics
  • 2.3 Transition from analogue to digital networks
  • 2.4 Centralized maintenance operations
• 3 Overall maintenance philosophy
  • 3.1 Maintenance entity concepts
  • 3.2 Failure concepts
  • 3.3 Network supervision
• 4 Bringing new international transmission systems and circuits into service
  • 4.1 Installation and acceptance testing
  • 4.2 Setting-up and lining-up
  • 4.3 Detailed considerations
  • 4.4 Bringing into service
• 5 Maintenance phases under normal and fault conditions
  • 5.1 Performance measuring
  • 5.2 Failure detection
  • 5.3 System protection
  • 5.4 Failure or performance information
  • 5.5 Fault localication
  • 5.6 Logistic delay
  • 5.7 Fault correction
  • 5.8 Verification
  • 5.9 Restoration
• 6 Additional maintenance activities
  • 6.1 Maintenance support
  • 6.2 Failure statistics
  • 6.3 Preventive maintenance actions
• 7 Other maintenance considerations
  • 7.1 Reference test frequency considerations
  • 7.2 Use of maintenance test lines and loop-backs
• References