The CellRanger is a wireless signal enhancer that can boost the number of bars you see on your iPhone in poor reception areas. However, simply increasing the number of bars isn't the whole story.

Description

The CellRanger, distributed by MOGO WIRELESS in Atlanta, GA, is a small device that connects to USB power on a PC or Mac and has an attached antenna. It's about the size of one of those car cigarette lighter adapters. In fact, a second version actually plugs into a car's cigarette lighter for power.

The basic idea is to receive cell phone signal in the 800 or 1900 MHz bands and retransmit it for your mobile phone, iPhone included.  It works with all carriers except Sprint/Nextel.

The 4-inch (10 cm) antenna is attached to a magnetic base for easy attachment to a car or boat. It can also be used in remote locations, such as when camping or at a house in a rural location with a poor signal.

Operation

I am one of those people who gets a marginal AT&T signal at our house, and my iPhone has been useless to marginal unless I leave the house. That's because we're in a slight topographic depression -- neighbors up the hill get a good signal. So I'm a prime candidate for a device like this.

In fact, I've tried several other makeshift solutions, some jury-rigged and some commercial and none have worked very well. The fundamental problem is that the iPhone doesn't have an antenna jack, and so proximity methods are required. (I have been told that GSM phones don't do well with antenna jacks, but I haven't been able to verify that claim.)

What's more, the idea of boosting the number of bars seen in the display, while attractive on the surface, isn't the whole story. In the past, I've described what's going on, and the canonical article on how the number of bars is calculated was written by Jacqui Cheng over at ars technica. The bottom line is that the number of bars displayed in a cell phone is not strictly a radio signal strength meter, but rather a complex calculation resulting in an estimate of your likelihood of completing a call.

Worse, in my testing of the device, I found that the number of bars is no guarantee of immunity from garbled or broken up voice. If the signal is weak to begin with, there will be dropouts. So the net result is that this device has its limits when it comes to very weak signals.

Testing

The CellRanger is the first and only device I've tested that can produce repeatable, improved results. That is, given that I have, for example, one bar without the device, I can demonstrate an improved number of bars simply by moving the cell phone close to the device. Pull it away, and the number of bars returns to the old state. This kind of repeatable, quantitative performance is very nice to see and gives one confidence that it really is working.

However, I encountered two problems. First, the manual says that the phone should be a few inches from the base unit. After some testing, I would say that the reality is that it needs to be a few centimeters from it. That means the dream of moving about my office while on AT&T remains distant. Instead, I jury-rigged a setup that combined a Just Mobile Xtand with the base unit so that when the iPhone is in the cradle, they almost touch. See the photos below.

Cell Ranger + Xtand

The second problem is that I have virtually no AT&T signal anywhere in my house. Recently, I found one sweet spot in my office that allows for, basically, a crappy quality call, but at least I can get through. The CellRanger improved the situation from barely usable to poor. Even though, at times, I see five bars on the AT&T iPhone, that doesn't translate into a crisp call with no dropouts. I wouldn't depend on it to replace my land line, but at least I can start to use some of those 4,000+ rollover minutes that I've accumulated.

With iPhone Cradled

The situation with my T-Mobile phone is better. We get fair to good T-Mobile coverage where I live and the CellRanger is able to take a decent signal and give me four bars and a solid, drop-out free voice call. Again, four bars on the T-Mobile phone results is a higher quality call than four bars on the AT&T iPhone. Chalk it up to the mysteries of radio science and the algorithm described above.

Conclusion

What I liked about the unit was the quantitative, observable change in the number of signal bars displayed on my mobile phones. However, to get that advantage, I had to rig up an arrangement where the phone is very close to the base and either use the speakerphone or earbuds. With Apple's iPhone earbuds, the quality of my calls on T-Mobile is as good as a land line, and the AT&T iPhone 3GS now becomes usable when, before, it was not.

Antenna At Top of Window

The USB powered or 12V powered version sells for $149.99. That's expensive, as devices like this go, but the payoff is that it actually does what it says it will do. My communications are improved, and I feel better about both my phones here in a rural area. That's good for now. At least until AT&T releases its femtocell/microcell Wi-Fi to 3G repeater for homes down the road. Presumably, at that point, I'll be able to make a call from anywhere in my house, and I can think about dropping T-Mobile.