This applications records the various cell network and data connection information for your phone. It helps to show why your Android phone is switching cell towers and connections types (3G to 2G, back to 3G, etc).
Using it, you can track what cell towers you are connecting to, the strength of the signal, etc and try to determine the parameters that the phone uses to switch cell towers. It was written for GSM phones. It works on CDMA phones as well, but the testing on CDMA phones is thus far limited.