What do the cell phone reception bars mean?

Can you hear me now? So much for the Cingular / AT&T ad campaign. (5 bar logo, biggest network, largest coverage don’t mean a thing if call quality sucks and you get dropped calls)

“They don’t mean much of anything, it turns out.

I don’t know what they’re displaying for GSM, but probably what they’re displaying is the signal strength. For CDMA (which is what I know about) that’s what they display, but in CDMA the signal strength is highly deceptive because it doesn’t inform you of what the noise floor is.

The technical term is “EC/I0” (pronounced “ee-see-over-eye-naught”) and it refers to the amount of the signal which is usable. In CDMA you can have strong signal (4 bars) and lousy EC/I0 and not be able to carry a call, and you can have low signal (zero bars) and excellent EC/I0 and carry a call fine. But they can’t display EC/I0 because it fluctuates wildly (it could go from zero to four bars and back to zero again in just a few seconds) and would terrify users, so they display the signal strength, which at least has the virtue of being stable, though it doesn’t really mean much.

Even worse… there is no industry standard for what “one bar” or “two bars” means. None. Everyone just sort of sets some thresholds, and even from the same manufacturer it can change from phone model to phone model.

Extrapolating from my CDMA experience, I would guess that in GSM they’re displaying the signal strength of the paging channel, with an uncalibrated display not driven by industry standards.” (link)

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1 Response to “What do the cell phone reception bars mean?”


  1. 1 James February 23, 2008 at 12:28 pm

    I have the same problem but with a Canadian company (ROGERS). They say that you have great reception all the time. I don’t think so. I have two bars on my screen right now instead of the five or so that are suppose to be there. It’s a bit frustrating.

    *Growls*


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