ONU or ONT?

In the ITU-T standards, Optical Network Unit (ONU) is the generic name for a device installed at a subscriber’s premises to convert fiber access interfaces to Ethernet, POTS, and other interfaces, whether the device is serving one or more subscribers. The current version of the G.984 GPON standard does acknowledge the need to differentiate between single-user and multi-user devices.

In common usage, an Optical Network Terminal (ONT) serves a single subscriber premises such as a stand alone house. An ONT has no need for security between its few interfaces and sells for perhaps a few hundred dollars. A typical indoor ONT is shown below.

ONU is used to describe a device serving multiple subscribers such as those in an apartment building or shared office building. It has a radically different architecture and is more similar to a DSLAM or Ethernet Switch than a single family ONT. An ONU can sell for several thousand dollars, depending on subscriber density, but often offers a lower per-subscriber cost than an ONT because common components are shared.

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