Network Signal Guru (NSG), but it needs root on phone and Qualcomm Chipset.
And free version does not allow decoding of messages or logging. Just viewing it
Paid version (full version) is 50 USD/month. You may think is expensive but is not. Think about TEMS or NEMO/Agilent that charges 20 times more.
I really enjoy this tool. Logs are saved in DLF format so you can view with QXDM or ACTIX or AIRSCREEN.
