What is the Difference Between OLT and ONT?

Learn > Fiber > What is the Difference Between OLT and ONT?

When you are setting up fiber Internet in your home or office, you come across an expansive list of abbreviations to understand. Among that list are things like PON, ONT, OLT, ONU, and more. Trying to understand these abbreviations and how they work together can be overwhelming. We will go through the ones you need to know and why. This way, you can better understand your Internet service provider (ISP) during the purchase and installation of fiber optic services (FiOS) in your space. 

We have articles explaining some of the devices and abbreviations you should know over on our Learn Page. But on this page we will cover OLT and ONT, what they are and what they do. Here is what you should know:



There are two devices that you need to know to understand how fiber works. They are OLT and ONT. 

  • OLT stands for Optical Line Terminal. An OLT is the device that serves as your ISPs endpoint of the passive optical network (PON). The OLT also provides the interface between a PON and your ISP’s core network. Simply put, an OLT is ISP equipment. 
  • ONT stands for Optical Network Terminal. An ONT is the device that serves as the telecommunication chain’s endpoint of the PON on your end. Another abbreviation to know is an ONU, which stands for Optical Network Unit. ONU and ONT are often used interchangeably. More or less, they are the same. Simply put, an ONT/ONU refer to the user side equipment.  


The Purpose of an OLT

The OLT is the device that exists at your ISPs central hub.

An OLT has a few purposes:

  1. Control the information flowing upstream and downstream.
  2. Convert the standard signals used by fiber optic service (FiOS) to the frequency and framing used by a PON system.
  3. Coordinate the multiple analog or digital signals that are combined into one signal (called multiplexing) that happens between the ONT conversion devices. 

The upstream channel transmits different types of data and voice traffic from users to the ISP. The downstream channel is what receives data, voice and video traffic and sends it to all ONT devices on your network. 


The Purpose of an ONT/ONU

The ONT/ONU is the device that exists at your home or office. 

The ONT acts as an optical modem and communicates with your ISP through a fiber optical cable. The ONT sends user data upstream to the OLT and receives data on the downstream channel. 

ONT and OLT are essential devices in a PON network system. Hitron offers ONT/ONU equipment with easy integration, flexible adaption and great reliability to meet all your requirements.

You can scale up your fiber network today with Hitron’s offerings of 10G PON ONT/ONU solutions. Hitron’s 10-Gigabit PON fiber interface is a high-powered device that delivers speeds up to 10 Gbps downstream and upstream. This makes downloading and uploading content super fast. This will greatly enhance your gaming and streaming experiences and more. 

Ask your ISP about Hitron’s offerings today. For more information on fiber optic networking, check out Hitron’s Learn Page

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