Motorola C975 3G User Manual page 34

Labels at the bottom corners of the display show the current soft
key functions. Press the left soft key or right soft key to perform the
function indicated by the left or right soft key label.
The following status indicators can display:
1. Signal Strength Indicator
Vertical bars show the strength of the network connection. You
cannot make or receive calls when the 1 (no signal) indicator or
0 (no transmit) indicator is displayed.
34 - Learning to Use Your Phone