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If you're in the market for a way to make sure you have cell signal inside your big home, Nextivity's Cel-Fi sure is a great find. The only question is if it's worth the investment.
The answer depends heavily on how much you need your cell signal. At the current cost of somewhere between $500 to $600, the Cel-Fi is quite a heavy investment for most homes, so rather, it's more suited for an office.
In my testing, the device worked well for both voice and data, as long as you don't expect support for 4G LTE (it supports only with 3G and the 4G HSPA+ standard.) It also only works with GSM cell signal and is carrier-specific. This means in the US you will need to buy one for T-Mobile and another for AT&T, which makes it that much more expensive.
Nonetheless, supporting up to 60 users at a time, the Cel-Fi is a good investment a large home or building where staying connected via cellular signal is a must.
Bulky design, plug-and-play setup The Cel-Fi comes in a set of two units, called Window unit and Coverage unit. The former is big, measuring 5.8 inches by 5.7 inches by 8.4 inches and looks like small computer sub-woofer speaker. The second unit is about one third of the size and look like a side computer speaker. The total weight of both is about 2.2 pounds. Each of the units comes with a power adapter and requires a wall socket to work. This means finding good place for them in a house can be a challenge, esthetically.
Setting them up, on the other hand is not a challenge at all. When you get a Cel-Fi at a store in the US it will be already tuned for either T-Mobile or AT&T and you won't need to contact the carrier for the setup.
First you need to place the Window unit at a place where cell signal exists (preferably by a window on a top floor). When plugged in, this unit has an array of lights that shows the bars that indicate the strength of the cell signal where it is, just like on a cell phone. Generally, you want to put it where you have the most bars, but a single bar is good enough.
After that you need to put the Coverage unit as far away from the Window unit as possible. This unit is the heart of desired cell signal coverage, of which the radius is the distance between the two units, so the further it is away from the Window unit, the larger the area its signal can cover. Of course there's a limit to how far the two can be apart before they stops working with each other. The only way to find out is to move the Coverage unit around, plug it in and wait for the sync icons on its surface to light up, which indicates there's sync between the two. In my testing, it took up to two minutes for the units to sync so it might take some time for you to find out the optimal distance you should place the Coverage unit from the Window unit.
Generally speaking, however, the two units connects to each other using the same 5Ghz frequency in Wi-Fi technology. That said, the distance between them varies from between 150 feet to up to 350 feet, depending on the environment. In optimal settings, a Cel-Fi set can offer up to 13,000 square feet of cell coverage with support for 60 connected units at a time. You can actually use multiple sets together to increase the coverage area and number of concurrent users. In my testing, there seemed to be a minimum distance, too, and the Window and the Coverage unit needed to be at least 50 feet away from each other sync up.
In all, it was very easy to set up a Cel-Fi set. Apart from finding out the right distance, the rest is just plug and play.
No support for 4G LTE In my trial, the Cel-Fi indeed helped a great deal with voice signal and I was able to make calls and hold a long conversation in places I couldn't before. The data also worked well. When the Cel-Fi was turned on, my test T-Mobile phone also showed full bars indicating the improvement in signal strength. But that was also because the phone was not tuned for 4G LTE. When I tried a 4G LTE device with the Cel-Fi, it had no affect on the bars as well as the cellular data speed. Nextivity says though the Cel-Fi doesn't support 4G LTE for data, it should helps with voice even when you use a 4G LTE phone with it.
For now the Cel-Fi supports only 3G and 4G HSPA+ standard. Nextivity says that going forward, there will be a newer version of the Cel-Fi that will also works with 4G LTE.
Performance It was a little hard to test the Cel-Fi due to the constraint of my environment and the fact that cell coverage, of both AT&T and T-Mobile, is generally good in the San Francisco Bay Area. But, as mentioned above, I was able to see the improvement, quite significantly for both data and voice. It's interesting that it worked well for voice even when the Windows unit showed only just one or two bars.
I was able to put the Coverage unit some 250 feet away from the Window unit and have them both synced up. (Note that I couldn't move it further due to a lack of wall sockets and maybe the distance could get even longer.) In this case, in theory, you should be able to get signal improvement up to 500 feet away from the Window unit as long as you stand directly across the Coverage unit. In my test, again, I couldn't move further away than some 300 feet, simply because I was already in the basement.
When used in a multiple-story home, the signal could penetrate to the basement quite easily. In all, the Cel-Fi indeed helps enhance the cellular signal where it's used.
Conclusion The Cel-Fi is truly a plug-and-play device that greatly improves cell signal. It's an excellent alternative to Femtocellsince it doesn't require a broadband Internet connection to work, allowing you to seamlessly continue your conversation when moving in and out of the house.
The device's main shortcoming is its cost, which is more than three times that of a Femtocell, making it only a viable solution for a business, rather than for a home. And the fact that there's no support for CDMA means Verizon and Sprint users are completely discounted, for now.