QoS

Quality of Service
 - Used to define the level of service and control the transmission of different types of traffic (voice, data, video).

QSIG

The protocol for networking telecommunications systems from different manufacturers.

Quad Fibre Cable

A type of fibre optic cable that has four single cables enclosed in an extruded jacket of polyvinyl chloride (PVC), with a rip cord for pulling back the jacket to access the fibres.