The iOS devices show the LTE signal bars (not voice all the time, regardless of connection) unlike the Android devices.
You can access the iOS field test menu by dialing *3001#12345#* then if you just press the HOME button it should leave the dBm visible instead of the bars until you restart your phone.
I know on Android devices you can dial ##DEBUG# to get the LTE signal strength (dBm). That doesn't work on the iPhone 5 though. Does the iPhone 5 have this feature? If yes, what do I need to dial to get the signal strength (dBm).