Cel-Fi by Nextivity builds operator-approved, network-safe cellular boosters that solve in-building coverage where the carrier signal won't reach. Their IntelliBoost® technology delivers up to 100 dB of gain, about 30 dB more than FCC-regulated consumer boosters, without violating carrier RF safety requirements.

The CEL-FI GO G51 FN is the most powerful 5G-capable FirstNet signal booster available in its class. Built on the 4th-generation Nextivity IntelliBoost chip, the G51 FN delivers up to 100 dB of gain across AT&T's full 4G LTE band set, FirstNet's dedicated band 14, and 5G NR on band n77, the C-band mid-band spectrum that modern AT&T smartphones increasingly default to indoors.

This is a single-carrier system. It amplifies AT&T and FirstNet signals only. Verizon, T-Mobile, and other carriers' signals are explicitly ignored, which is why the G51 FN is exempt from the FCC's 70 dB consumer-booster cap. The trade-off is straightforward: if your facility is on AT&T or FirstNet, you get roughly 11× the coverage area of a multi-carrier consumer booster. If you need to support multiple carriers, the CEL-FI GO G43 FN does multi-carrier and FirstNet in one chassis.

The G51 FN is built for government buildings, fire and police stations, schools, hospitals, and large commercial spaces; anywhere on AT&T or FirstNet that needs indoor cellular coverage holding up when the macro network is weak, including the mid-band 5G C-band (n77) that smartphones increasingly default to. The system is operator-approved, unconditionally network-safe, and 3GPP Release 17 NR-compliant, which matters when deploying in regulated environments where the booster has to coexist with the carrier's macro network without causing interference.

If you don't need 5G yet, the GO G41 FN is the 4G-only sibling at a lower price. If you need multi-carrier coverage (Verizon and T-Mobile too), look at the GO G43 FN. For campuses larger than ~15,000 sq ft, you're past what a single G51 covers. Talk to us about a QUATRA 4000 active DAS deployment.

Real 5G NR on n77, not just 4G with a "5G-ready" badge

The G51 FN is one of the first FirstNet boosters with true 5G NR amplification on band n77 (3.7 GHz C-band), the mid-band spectrum that AT&T uses for the bulk of its 5G capacity. Up to 100 MHz of channel bandwidth and 27 dBm downlink power means modern smartphones get the full 5G experience indoors, not just a 5G icon over an LTE connection.

100 dB of gain, about 11× what consumer boosters can do

Cel-Fi's IntelliBoost technology is operator-approved and unconditionally network-safe, which means the GO G51 FN is exempt from the FCC's 70 dB cap that limits consumer boosters. The result is 100 dB of system gain, about 30 dB more amplification than off-the-shelf alternatives, and roughly the coverage area of 11 competing devices combined.

Plug-and-play self-configuration

There's no manual tuning, no spectrum analyzer, no installer-mode commands. Power the unit up, run the Nextivity WAVE app on your phone (Bluetooth), pick the operator, and the 4th-generation IntelliBoost chip handles channel selection, gain calibration, and band optimization on its own. A 3GPP Release 17 NR-compliant device that behaves predictably the first time and every time.

WAVE Portal remote monitoring for IT and integrators

The RJ45 LAN port connects the GO G51 FN to Nextivity's WAVE Portal: real-time system health, gain levels, signal strength, and alerts, viewable from any browser. Useful for managed-service deployments, multi-site customers, and integrators tracking SLAs.

Key Features of the GO G51 FN

• 5G NR on band n77 (3.7 GHz C-band): up to 100 MHz channel bandwidth, 27 dBm downlink, 24 dBm uplink
• 4G LTE on AT&T + FirstNet bands: B2 (PCS), B12, B14 (FirstNet), B17, B25
• 100 dB of system gain, about 30 dB more than FCC-regulated consumer boosters
• Operator-approved and network-safe, exempt from the FCC 70 dB cap on signal boosters
• 3GPP Release 17 NR-compliant, future-proof for additional 5G features
• Self-configuring via IntelliBoost: no manual tuning, no installer mode, no spectrum analyzer required
• Dual-band relay: simultaneous 4G LTE + 5G NR amplification, not a tradeoff
• 30 dB minimum echo cancellation, enterprise-grade isolation between donor and server antennas
• WAVE App setup over Bluetooth LE 4.2: installer pairs from iOS or Android, no laptop required
• WAVE Portal cloud monitoring over LAN: real-time diagnostics, remote management, alerts
• USB 2.0 Micro-B for WAVE Field Tool: installer diagnostic interface
• Passive convection cooling: no fans, no maintenance
• Compact wall-mount or ceiling-mount chassis: 10.44 × 6.77 × 2.72 in, 4.8 lbs
• Indoor-rated (IPX0): drop-ceiling or wall mount; the donor antenna goes outdoors

Carrier Support and Bands

Operator support: AT&T® and AT&T® FirstNet®. Single-carrier system, network-safe and operator-approved.

5G NR bands: n77 (3.7 GHz C-band)

4G LTE bands: B2, B12, B14 (FirstNet), B17, B25

The G51 FN does not amplify Verizon, T-Mobile, US Cellular, or other carriers. For multi-carrier coverage with FirstNet, use the GO G43 FN.

Specifications

Spec	Value
System gain	100 dB max
Echo cancellation	30 dB min
Networks	2G / 3G / 4G LTE / 5G NR
Bands (Americas FN)	n77 + B2 / B12 / B14 / B17 / B25
Channel bandwidth	Up to 100 MHz on n77; 5 / 10 / 15 / 20 MHz on LTE
Output power downlink (n77)	27 dBm max
Output power uplink (n77)	24 dBm max
Donor / server RF connectors	SMA (f) on both
Impedance	50 Ω
Management	Nextivity WAVE App (Bluetooth LE 4.2), WAVE Portal (LAN), WAVE Field Tool (USB 2.0 Micro-B)
Power consumption	60 W max
AC adapter	Included (Nextivity 290N134-010, 60 W, 1 m DC cable, 6 ft AC cable)
Dimensions	10.44 × 6.77 × 2.72 in (265.2 × 172.0 × 69.2 mm)
Weight	4.8 lbs (2.2 kg)
Operating temperature	32 to 104 °F (0 to 40 °C)
Ingress protection	IPX0 (indoor only)
Cooling	Passive convection (no fans)
Compliance	3GPP TS 38.106 Rel 17, FCC operator-approved booster

Kit Contents

• 1× CEL-FI GO G51 Main Unit
• 1× AC Adapter (Nextivity 290N134-010, 60 W) with 6 ft AC cable + 1 m DC cable
• 4× Mounting screws
• 4× Drywall anchors
• 1× Ethernet cable (Cat-5e or better)
• 1× Quick Installation Guide

* Antennas and RF cable are sold separately. The G51-CE-003 is an amplifier-only kit. For most deployments you'll also need: one donor antenna (typically A21-ML3-600 whip or A62-V44-201 LPDA for weak-signal sites), one or more server antennas (A11-V43-121 dome or A41-NL3-100 omni patch are common), and SMA-terminated LMR195 or RG58 RF cable in the appropriate run length. Our team can spec the antenna kit for your site. Contact us.

Frequently Asked Questions

How is the GO G51 FN different from the GO G41 FN?
The G51 FN adds 5G NR on band n77, the mid-band C-band spectrum that AT&T is rapidly building out for 5G capacity. The G41 FN is 4G-only on AT&T and FirstNet, and was sold as "5G-ready" but does not actually amplify 5G NR carriers. If your facility's traffic is increasingly on 5G phones (most iPhones from the 12-series onward, most recent Samsung devices, etc.), the G51 FN keeps the 5G experience working indoors. If your users are still primarily on 4G LTE devices, the G41 FN is cheaper and does the job.

Does this include antennas and RF cable?
No. The G51-CE-003 is an amplifier-only kit. You'll need a donor antenna (mounted outdoors, pointing at the nearest cell tower), one or more server antennas (mounted indoors, distributing the boosted signal), and 50-ohm SMA-terminated RF cable connecting them to the G51. We sell all of these and can recommend a configuration for your site. Most deployments use a 20 ft to 30 ft cable run on the donor side and 30 ft on the server side. Contact us for a site-specific quote.

Is this FirstNet-approved?
Yes. The G51 FN is operator-approved by AT&T and unconditionally network-safe, which is what allows the 100 dB gain (exempt from the FCC's 70 dB consumer-booster cap). It's deployed in fire stations, police stations, EOCs, and other public-safety facilities that depend on FirstNet's dedicated band 14.

What coverage area can I expect?
It depends on the outdoor signal quality and the number of server antennas you deploy. In favorable conditions (good outdoor signal, open-plan interior, 2-3 server antennas), a single G51 FN can cover up to about 15,000 sq ft at peak. In a typical office or commercial environment with internal walls and a single server antenna, plan for around 10,000 sq ft. Coverage scales with the number of server antennas. As a rule of thumb, one antenna per 1,000 to 1,500 sq ft in walled environments, one per 1,500 to 3,000 sq ft in open floor plans. For sites larger than this, you're looking at QUATRA 4000 active-DAS territory.