Pix,
In our project we dont use C2 parameter, Because all our BTSs are in remote places. So you can check and let me know. Other thing,
by changing rx minimum access level, we can definitely expect the changes in signal bars.
for ex if u put -90dBm as RX-min-acc then, when ur receving level is -90dBm, u will not get any signal bars in ur phone.