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Openreach FTTP ONT

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This page is about the FTTP termination device that Openreach install for FTTP customers. ONT stands for Optical Network Terminal, sometimes (mistakenly) called an openreach modem. CityFibre use a different ONT - we have a separate page on that: CityFibre ONT

(Newer) Openreach single port ONT - Lights show all good
(Older) Openreach ONT - Lights show all good

(Newer) Openreach single port ONT ports
(Older) Openreach ONT, powered off!
(Older) Openreach ONT, powered on and working OK
(Older) Openreach ONT, cover removed. Customer router connects to yellow socket


  • In short, the ONT in installed inside the customer's premises by CityFibre and converts the fibre connection from the outside world in to a RJ45 port which you plug in to your router with a CAT5 cable.
  • The ONT requires power, and a UPS is recommended, see our VoIP_Power page for suggestions.

Openreach provide an ONT for use with FTTP services. - so when you order a BT-based FTTP service from A&A, an Openreach engineer will install the little ONT unit in your premises. You then connect your Ethernet router to it and set your router with the A&A PPP credentials to log in.

This page is about diagnosing problems with the Openreach ONT.

  • A working Openreach unit has green: power, PON & LAN lights, anything else indicates a problem.
  • Your PPPoE capable router will plug in to the LAN port and connect you to the internet.

More info

  • Newer ONT installs do not include a Battery Backup Unit (BBU) See: 999_and_faults
  • Older Openreach ONT (Optical Network Termination) such as the one pictured, is actually inside the enclosure. This also contains a Battery Backup Unit (BBU) along with various wiring and cable management.
  • The ONT requires power, so will need a mains power socket nearby.
  • Where provided, the battery has a short warranty, and should be maintained by the end user, however, the battery is to keep the unit powered so that the TEL ports can be used during a power outage - we don't use the TEL ports, so you will want to make other arrangements for using a phone during a power outage - eg a mobile phone. See: 999_and_faults

Openreach ONT LED Status

Openreach ONT LED Status
LED Colour Meaning Notes
Top (ONT) LEDs
TEL1 Off We don't use the Tel ports
PORT1 or LAN Blinking/Flashing green Data being transmitted Good
Off ONT has no ethernet link to the router Bad. Check the connection/cable to the router
LOS (Loss of service)

PON (Passive Optical Network)
PON solid green, LOS off Connected and should be working Good. This is how it should be normally
PON flashing green, LOS off ONT is starting up Wait a bit for steady green and all should be well...
PON off, LOS solid red Possible fault with the fibre Bad. Check fibre not damaged, reconnect fibre, power cycle ONT
POWER Solid green Device has power Good
Off Power is off Bad. Check mains power and connection to BBU/ONT
Bottom right (BBU) LEDs
STATUS Solid green Good
FAULT Solid red Battery fault Bad. Replace the AA batteries inside
Off Good. No fault
CHARGING Solid orange Batteries are not fully charged Wait; the batteries are charging (usually after a power cut)
Off Batteries are not being charged Good. The batteries are fully charged

External links