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.