I have been in the telecom industry for many years. I bought it because it seems to be the best of the best. However, this is incredibly frustrating. Seems to get stuck in "Lock" mode ("Data Discovery and Lock on Talk") FREQUENTLY. This is to help you not disturb data lines (T1 and DSL), but this is rare these days. We rarely come across this and I wish there was a way to disable this "feature". Unfortunately, it cost me a lot of time while struggling with my own stocks and I regret not buying it. It often goes into this mode on its own, even if I don't seem to approach any data circles. (I hope Fluke can find a way to avoid this.) That being said, I like that it shows the voltage on the line I'm connecting to.