O

Object Mobility Location Transparency
     Location Transparency. The ability to move an Object from one machine or LAN to another without disrupting operations or  modifying source code.

OC - Optical Carrier
    Transport levels defined for SONET.   Levels include but are not limited to:   OC-1 = 1 DS3, 28 DS1, 672 DS0;   OC-3 = 3 DS3, 84 DS1, 2016 DS0;  0C-12 = 12 DS3, 336 DS1s, 8064 DS0s; OC-48 = 48 DS3s, 1344 DS1s, 32256 DS0s; and OC-192 = 192 DS3s, 5376 DS1s, 129,024 DS0s.

OCC - Other Common Carrier
      Carriers providing long distance communications service.  Not part of the original AT&T system.

OCEF - Optical Cable Entrance Facility
    An area providing space for splicing fibers connecting equipment to outside plant.

OCR - Optical Character Recognition
    Reading data using a machine that visually scans the characters in a document and converts that data into standard form which can be stored on conventional magnetic medium, e.g. floppy or hard disk.

Octet
    A term for eight (8) bits that is sometimes used interchangeably with "byte" to mean the same thing.

OCUDP - Office Channel Unit Data Port
    A channel bank unit used to interface between the channel bank and the customer's DDS CSU or DSU.

Odd Parity
    One of many methods for detecting errors in transmitted data.  An extra bit is added to each character sent and  that bit is given a value of 0 (zero) or 1 (one) such that the total number of ones in the character will be odd.

Off Hook
     The signal that the telephone receiver has been lifted (activated). Originating off hook activates a dial tone on switched  networks. Destination off hook completes a call (and activates minute-by-minute billing for long distance calls).

Office Repeater Bay - ORB
    Equipment that provides the interface between a T-carrier circuit and the DSX.  It regenerates the incoming signal to the DS-1 level and provides line powering to the outside plant repeaters.

Off-Net Calling
    Phone calls which are carried in part, on a network but are destined for a phone not on the network (i.e. some part of the conversation's journey will be over the public switched network or over someone else's network.

On-Hook
    When the phone handset is resting in its cradle.  The phone is not connected to any particular line.

One Plus - 1+
     Customer ability to access the long distance service provider of their choice by first dialing 1, then the long distance number.  Equal Access guaranteed by the 1982 AT&T MFJ. 1+ is an outbound service where the calling station pays the charges.

On-Net
    Telephone calls which stay on a customer's private network, traveling by private line from beginning to end are said to be on-net.  In other words, there are no leased components within the communication path of the circuit.

One-Way Trunk
    1. A trunk between a switch (PBX) and a central office, or between central offices, where traffic originates from only one end.  2. A trunk circuit which can be seized at only one end.

OOF - Out Of Frame
    Condition counter that increments every time either the network or the DTE equipment senses an error in the framing bits of a circuit or device.

Operator
    Employee of telephone company, or an individual business or institution, who aids in the completion of phone calls.

Operator Service Call - OSC
     A call that is placed through a human or automated operator (0+) .

Operator Service Provider - OSP
    A new breed of long distance phone company which handles operator-assisted calls - in particular, Credit Card, Collect, Third Party Billed and Person-to-Person.

Optical Amplifier
    A device to amplify an optical signal without converting the signal from optical to electrical back again to optical energy.

Optical Attenuator
    In optical communications, a device used to reduce the intensity of the optical signal.

Optical Fiber
    Any filament made of dielectric materials, that guides light, whether or not it is used to transmit signals.  It is almost the ideal transmission medium because of: 1. Transmission losses are very small. 2. Bandwidth is greater than any other transmission medium known today. 3. Fiber is immune to electromagnetic interference.  4. Fiber does not radiate. 5. Many strands of fiber carrying much information can be put in the same bundle and they won't interfere with each other. 6. It's raw material, silica (sand) is the second most abundant element on earth.

Optical Time Domain Reflectometer - OTDR
    A device that measures distance to a reflection surface by measuring the time it takes for a lightwave pulse to reflect from the surface.  Reflection surfaces include the ends of cables and breaks in fiber.  Heavily used during fiber cuts to locate the exact point of the cut.

OPX - Off-Premise Extensions
     A station line at a location other than the premise where the PBX (or local exchange service) is located.

Order Wire Circuit
    A voice or data circuit used by telephone company technical control and maintenance personnel for the coordination and control action relating to activation, deactivation, change, rerouting, reporting and maintenance of communication systems and services.

Originator
     The person, location or ANI that initiated a call, order, etc.

Outbound
     Outward Sending - Call Originating - Dialing Out.

Out-Of-Band Signaling

1) The use of transmission facilities other than the primary channel bandwidth for simple transmission control pulses. Contrast with in-band signaling. 2) The use of narrow band filters to place the voice signal on a carrier channel below 3,400 Hz, reserving the 3,400 - 3,700 Hz band for supervisory signals.

Outpulsing
    The process of transmitting address information over a trunk from one switching center to another.

Overflow
    Additional traffic beyond the capacity of a specific trunking group which is then offered to another group or line.

Overhead
    In communications, all information such as control, routing and error-checking characters, that is in addition to user-transmitted data.

Oversubscription
     In frame relay service definition, over subscription occurs when the sum of the CIRs for all PVCs on a port exceed the port  connection speed. Subscription levels of 200% are typically allowed. Oversubscription is possible because of dynamic  capacity allocation in modern data networks.