 Open Network Architecture. Numbering Plan Area. Open Network Doctrine. (Japanese plan for equal Null Point Indication. access.) Network Performance Parameters. Operator Number Identification. (Operator used in a Noise Power Ratio. CAMA office to verbally obtain the calling number Non Return to Zero. (A binary encoding technique for calls originating in offices not equipped with for transmission of data.) ANI.) Non Return to Zero Inverted. (A binary encoding Open Network Provision. techniqe for transmission of data.) Optical Network Termination. (Termination point Network Service Access Point. (Prime address point for optical fibre access system.) used within OSI.) Object Oriented Design. (Software design tech- Network Termination. (Termination designed within nique.) ISDN e.g. NT1 and NT2.) On-Off Keying. (Digital modulation technique. Also Network Terminating Equipment. (Usually refers to known as ASK or Amplitude Shift Keying.) the customer termination for an ISDN line.) Object Oriented Programming. National Telecommunications Industry Administra- Operating System. (Or Operations System. CCITT.) tion. (USA) Outstation. Network Terminal Number. (Part of an international One Stop Billing. telephone number.) Open Software Foundation National Television System Committee. (US.) Operations System Function. (CCITT.) Nippon Telegraph and Telephone. (Japanese car- Open Systems Interconnection. (Refers to the seven rier.) layer reference model.) Network Terminating Unit. (Used to terminate sub- OSI Environment. scriber leased line.) OSITOP Open Systems Interconnection Technical and Office Protocol. Operator Service Provider. (Company in the USA Operations, Administration and Maintenance. (Also providing competitive toll operator services for bill- written as OAM.) ing and call completion.) OAM&P Operations, Administration, Maintenance & Provi- One Stop Shopping. sioning. Optical Time Domain Reflectometer. Object & Attribute Management. (NM Forum.) Orbital Test Satellite. Operations & Maintenance. Optimum Working Frequen