I-211M-L ONT: Enable Data While on Battery Power

The I-211M-L Optical Network Terminal (ONT) is a popular endpoint for subscribers of fiber internet, or fiber-based phone (POTs) and video services. New Verizon FIOS installations tend to use this ONT.

Unlike previous ONTs, the I-211M-L does not come with a battery backup. A power glitch or brownout may cause the unit to reset, interrupting internet connections, phone calls, and TV signals. Verizon sells a battery backup accessory (ReadyPower) that uses 12 D-cell batteries. However, it only supplies power to keep POTs active. Data and video remain offline.

This instructable will show how a quick, reversable modification of the power supply cable will allow a battery backup accessory such as ReadyPower to continue providing data and video services in addition to POTs.

Be advised that this mod is not sanctioned by your ISP. You remain solely responsible for damage arising from following these instructions.

Step 1: Disconnect the Power

Disconnect the AC power cord from the power supply unit (PSU). Ensure that no other power sources are connected to the PSU.

Step 2: Disconnect the Power Cord to the ONT

The ONT is connected to the PSU by a 9-pin mini din (type B) cable. Disconnect this cable from both the PSU and ONT.

Step 3: Identify Power and Signal Pins on the Connector.

Pins 8-9 are ground. Pins 1-2 provide +16V. Pin 4 is normally pulled low when the PSU is under AC power. It is floating when on battery power. Pins 3,5, and 6 do not appear to be used.

Step 4: Carefully Ground Middle Row of Pins

Pin 4 appears to be the only active pin in the middle row. Pins 3,5, and 6 are not used. An easy way to always pull pin 4 low is to ground it with pins 8-9.

Take a strip of foil and fold it in half. Carefully cut a small 4mm x 1.5mm piece at the fold and insert between the middle row (with 4 pins) and top row (with 3 pins). Do not let anything touch pins 1 and 2 (bottom row).

Reconnect this end to the ONT. Connect the other end of the cable to the PSU.

Note: The foil insert must be thin, so you can plug the connector back in with the insert wedged at the base of the plug. Too thick and you may bend pins plugging it back.

Step 5: Locate the Auxilary Power Port on the ONT Power Supply Unit

The PSU (e.g. CyberPower CA25U16V2) provides power to the ONT from the AC outlet. On the side of the PSU is an auxiliary power port. A DC power source providing 12-18VDC @ 1A can be used. The port requires a 1.3mm x 3.5mm jack. Connect the ReadyPower accessory (or other DC power source) to this port.

Step 6: Turn on DC Power Source

Without connecting the PSU to AC, supply power to the PSU using the auxiliary power port. The ONT will boot and enable data, video, and POTs after it has finished booting.

Step 7: Wrap Up

Turn off auxiliary power and reconnect AC to the PSU. Now when a power failure occurs, turn on your battery backup and the ONT will run on battery. The ONT will provide data, video and POTs, unlike before where only POTs will work.