I've only used it a few times so far. The problem with the VoIP phone turned out to be that the cable was too long. It seems that the port does not blink too long a cable. I don't find the audio very sensitive when connected to a switch. It's supposed to work over the power cord, but I'll have to test it further to see if it works or not. DO NOT leave the battery connected to the toner. If you put it in the case, it will press the flashlight button and drain the battery. I drained two batteries before discovering this. Now I disconnect the battery before I put it in the case.