Open Box: Cel-Fi DUO+ for T-Mobile

by Cel-Fi


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Product Description

This is an open box item.  The product will contain all original parts and accessories and is in like new condition.  Open Box items may contain superficial scratches that do not affect performance.  All open box units are sold AS IS and can be returned within 30 days from receipt of the product. 

The Cel-Fi DUO+ (D32-2/4/12) is a powerful signal booster system that boosts T-Mobile 4G LTE voice and data. The Cel-Fi DUO+ offers up to 100 dB of gain and coverage up to 15,000 sq ft.

The DUO+ covers Band 2, Band 4, and Band 12 for T-Mobile. It requires at least one bar of LTE signal where the network unit will be located.

The Cel-Fi DUO+ system is very easy to set up. Anyone can install the device. No special tools or knowledge is required and there are no external cables, antennas, wires, or drills needed. The units simply plug-in to power. 

The Cel-Fi DUO+ has an LCD color interface which provides instant visual feedback. It is fully self-contained and self-configuring. No ongoing maintenance is needed. 

The DUO+ is best for T-Mobile users looking for an easy installation of a powerful signal booster without running cable or mounting outdoor antennas. It will boost any device using T-Mobile within the coverage area.

Cel-Fi WAVE Mobile App

Cel-Fi WAVE is a smartphone app that will help you get the best performance from your Cel-Fi DUO+. The WAVE app is available for desktop, iOS, and Android. The app’s dashboard gives you a real-time overview of the system performance and allows you to optimize setup and download software updates.


The Network Unit (NU) should be placed where the existing cellular signal is best (generally by a high window). The unit requires at least one bar of signal to work. The Coverage Unit (CU) should be placed in the location you need improved signal. You can optimize coverage by moving the CU. The NU and CU communicate with each other wirelessly to provide the best signal improvement possible. Red and Green icons on the CU LED user interface will indicate whether the CU should be closer or further from the NU.


Mounting brackets and hardware are provided to mount either/both the Coverage Unit and the Network Unit. The brackets come equipped with screws and inserts for mounting in standard drywall. 

The DUO+ comes with a 2-Year Warranty.

How it works

1 - Outdoor antenna

The outdoor antenna receives and transmits signal to nearby cellphone towers. Outdoor antennas can be either directional or omni-directional.

2 - Cellular amplifier

The amplifier (or "repeater") boosts the signal coming to and from and going to the cell phone tower. The "gain" of the amplifier describes how strong the amplification is - you'll see that word scattered across our product pages.

3 - Indoor antenna

The indoor antenna rebroadcasts the signal inside the building. Some kits have more than one indoor antenna to help distribute the signal.

how a cell phone booster works


The coverage area you can expect from any signal booster kit depends on the signal strength outside the building.

Outdoor Signal Estimated coverage area
Strong outdoor signal (5 bars) up to 15,000 sq. ft. coverage
Medium outdoor signal (3-4 bars) up to 10,000 sq. ft. coverage
Weak outdoor signal (1-2 bars) up to 7,500 sq. ft. coverage


Like almost all of our products, the Open Box: Cel-Fi DUO+ for T-Mobile can be installed by anyone who feels comfortable doing simple home repairs and running cabling. If you’re not comfortable doing that kind of work, you might consider finding a local electronics installer or asking a friend.

Unlimited free technical support:

Anytime you purchase from Waveform, you get unlimited free technical support from our signal experts. Whether it’s installing a kit or troubleshooting a problem, we’re here. In over 11 years of being in business we’ve helped over 25,000 customers install kits and improve their signal.

Have a question now? Call us from 7am to 5pm PST: 1-800-761-3041.

Product video


Coverage 7500 sq ft (1 coverage with weak signal)
10000 sq ft (2 coverage with medium signal)
15000 sq ft (3 coverage with strong signal)

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