Bar ranges are changed in the software including the minimum for 1 bar. You may be thinking of the "minimu" as zero signal, which is not the case. The minimum is simply defined as the attenuation as which the device can no longer maintain a connection. It's not a "hard coded change" just a software display change, doesn't mean it'll actually hold a call with that low signal.
Yes I think I understand what you're saying. What I'm saying is that at -121dBm, our phone now shows 1 bar when before it would show no signal. Whether or not it will hold a call at -121dBm is another story.