How Cel-Fi booster technology conquers mobile dead zones

Have you ever been stuck in a frustrating situation where your phone signal drops to zero bars? Maybe it happens at home, camping in the outback, or even in an office with metal walls. This dreaded “dead zone” can leave you feeling disconnected and helpless. But fear not—there’s a potential solution called Cel-Fi that acts like a signal booster of sorts.

What is a Cel-Fi?

Think of a Cel-Fi as a mini cell (mobile phone) tower for your home, office, or vehicle. It acts like a signal booster, grabbing a weak mobile signal and amplifying it indoors or in your car. This can significantly improve your call quality, text message reliability, and data speeds.

cel-fi roam r41 pack

Benefits of a Cel-Fi

  • Improved Connectivity: A stronger and more reliable cellular signal is the most obvious benefit. This means clearer calls, fewer dropped connections, and faster internet browsing on your phone.
  • Reduced Radiation: When your phone struggles with a weak signal, it has to work harder to transmit and receive information. This can lead to increased radiation exposure. By boosting the signal, Cel-Fi allows your phone to operate at lower power, potentially reducing radiation.
  • Wider Coverage: Cel-Fi can extend mobile coverage to areas where it’s normally weak, like basements, metal buildings, or rural locations. This can be a game-changer for people who live or work in areas with poor reception.
Roam R41
Roam R41

How Cel-Fi booster technology works

Imagine a Cel-Fi system as a two-person relay team for your phone signal. Here’s the breakdown:

Cel-Fi setup
Cell Tower communicates with Donor Antenna. Smart phone with Server Antenna.
  1. The receiver (Antenna Unit): This unit acts like the first runner. It’s typically placed outside your home, office, or on your car (depending on the model). An antenna designed for your use scenario catches weak cellular signals from the cell tower.
  2. Amplification and rebroadcast (Coverage Unit): This unit is like the second runner. It receives the weak signal from the antenna and strengthens it using an amplifier. Imagine the runner taking a breath and shouting the message louder. Finally, the Coverage Unit rebroadcasts the amplified signal through the server antenna inside your home, office, or car.
Cel-Fi server antenna
Cel-Fi server antenna.

Avoiding Interference

Here’s the tricky part: Cel-Fi needs to be smart to avoid causing problems for the cellular mobile network. Imagine multiple runners shouting the same message simultaneously – it can get messy. A Cel-Fi can compete with a carrier’s existing mobile phone towers and frequencies. To overcome this, the Cel-Fi will:

  • Listening before shouting: The Cel-Fi receiver unit constantly monitors the cellular network signals to understand the traffic.
  • Smart amplification: Based on this information, Cel-Fi only amplifies weak signals and avoids boosting strong signals that could interfere with the network.
  • Carrier coordination: Cel-Fi works directly with your cellular carrier. This allows Cel-Fi to adjust its behaviour based on real-time network conditions and even remotely shut down if necessary to avoid causing issues.

The amount of boost a Cel-Fi provides depends on the specific model and the situation, but here’s a breakdown to give you an idea:

Cel-Fi’s Boosting power

Cel-Fi boasts a maximum potential gain of 100 decibel milliwatts (dBm), a significant boost compared to the signal your mobile phone will receive. However, it’s important to understand that this is the theoretical maximum, and real-world results may vary.

Factors Affecting Boost Strength:

  • Model: Different Cel-Fi models cater to various needs and offer varying boost levels. We previously reviewed the Nextivity R41 Roam sold by RFI in Australia, and the review discusses other models available locally.
  • Signal strength: The strength of the incoming signal plays a big role. A stronger incoming signal allows for a more significant boost.
  • Installation: Proper antenna placement is crucial for optimal performance. The two Cel-Fi antennas must be far enough apart to minimise interference.
  • Environment: Building materials, surrounding terrain, and distance from the cell tower can impact the final boosted signal.

Understanding the “BOOST” Indicator on the Cel-Fi WAVE

Some Cel-Fi models come with the Cel-Fi WAVE App. This app provides valuable information, including a “BOOST” indicator. This number reflects the effectiveness of the Cel-Fi system in your specific situation, not necessarily the raw dBm boost.

Wave App

Here’s a general guideline for interpreting the BOOST indicator:

  • 7-9: Excellent boost in a stationary setting.
  • 6-8: Good boost, typical for most mobile installations (cars, boats).
  • Below 6: Lower boost, consider optimising antenna placement, or the signal may be too weak for significant improvement.

Debunking Cel-Fi misconceptions

Many users see full signal strength on their smartphone when connected to a Cel-Fi. This does not mean they have full signal strength back to the mobile phone tower; it means the user has full signal strength back to the Cel-Fi. A true indication can only be gained by reviewing the Cel-Fi WAVE App and the “Booster Receive Quality.” It is possible to have no coverage, but your phone shows full signal strength, and you cannot make a call.

While Cel-Fi will boost a signal, it only boosts a single cellular frequency or channel, in the case of R41. To have high-speed data, your smartphone may use up to four channels. See our practical test to understand the implications of data speed using a Cel-Fi.

The following terms are defined as follows:

  • Cellular frequencies: Cel-Fi operates on specific radio frequencies used by your cellular carrier (e.g.,5G, 4G and 3G frequencies).
  • Signal strength: Measured in decibel-milliwatts (dBm), this indicates how strong a cellular signal is. Cel-Fi amplifies weak signals (typically below -80 dBm) to improve your reception.
  • Gain refers to how much a Cel-Fi increases the signal strength.

Things to consider before buying a Cel-Fi

  • Legality: Cel-Fi devices operate on specific frequencies and are approved for use by Australian carriers in Australia, but they require registration.
  • Carrier choice: Whilst Telstra has the greatest coverage by land mass in Australia, Optus and Vodafone do work in places Telstra does not. Carrier choice is important, and the Roam R41 can be switched between Telstra, Vodafone and Optus. One at a time, and you will require a phone plan/s except for emergency calls to 000.
  • Installation: Some Cel-Fi models require professional installation, while others are designed for DIY setup. Consider your technical expertise before making a purchase.
  • Coverage area: The size and strength of the boosted signal will depend on the specific Cel-Fi model and your environment. Remember, a Cel-Fi cannot boost a signal if there is none.
  • Cost: Cel-Fi devices can range in price depending on features, starting at around $1,000 for the entry-level solution.

Cel-Fi mobile booster alternatives

Before investing in a Cel-Fi, consider some alternatives:

  • Sattelite phone: Requiring an additional satellite phone and plan will give coverage anywhere in Australia where you can see the sky.
  • Wi-Fi Calling: If you have a strong Wi-Fi connection, you can use Wi-Fi calling to make and receive calls over Wi-Fi instead of the cellular network.

By understanding the benefits and limitations of Cel-Fi, you can make an informed decision about whether it’s the right solution for your connectivity woes.

Is a Cel-Fi mobile phone booster right for you?

This guide is a simplified explanation. Cel-Fi technology is quite complex.  While Cel-Fi offers a powerful boost, the results will depend on your situation. Managing your expectations and understanding that the 100 dBm maximum gain is a theoretical limit is important.

Many people could benefit from using Cel-Fi booster technology, including anyone living or working in rural locations. Even homes and buildings located in decent network areas may still produce poor reception due to interference from construction materials like metals. If your work requires frequent travel and you need reliable connectivity for emergencies, a Cel-Fi booster could come in handy.