Glossary

O

OC
Optical carrier: a range of digital signals that can be carried on a Sonet fibre-optic network.
OFDM
Orthogonal frequency division multiplexing
Off-net call
Calls carried in part on a network but destined for termination on another network.
OLT
Optical line termination (see ONU)
OMA
Open Mobile Alliance
ONU
Optical network unit: a device that terminates an optical circuit at the customer premises, curb or neighbourhood.
Open access (duct)
Where retail or wholesale service providers share the use of a duct network by drawing or blowing their fibre cables through the shared ducts, and then compete on services.
Open access (fibre)
By connecting at the physical layer interface, multiple retail or wholesale service providers can use the same FTTH network and compete to offer their services.
Open access (packet)
Where multiple retail service providers share the FTTH network by connecting at a packet layer interface and then compete to offer their services.
Open access (wavelength)
Where multiple retail or wholesale service providers may use the FTTH network by connecting at a wavelength layer interface and compete to offer their services.
Open Connectivity
The GSMA Open Connectivity Programme was established in 2005 to facilitate easier and quicker interworking and roaming between GSM operators.
OSI
Open Systems Interconnection reference model that organises the communications process into seven distinct and sequenced layers.
OSPN
Open service provider network (Dynamic City): separates the infrastructure owner (the municipality or more commonly, a partnership between the municipality and private investors) from the wholesale operator of the infrastructure.
OSS
Operations support subsystem
OTDR
Optical time domain reflectometer: a measurement device used for testing the accuracy of fusion splices in a fibre-optic network.