Later models of this application kit (rebuilt), including the one I bought and received from Revain, have a fatal defect. If you call ON SPEAKERPHONE with a thousand-cycle tone, an ANI number, or even a person, and the phone line you are connected to has a high loop current (possibly more than 50mA), the microprocessor will, if you use the Answer line resets, the display lights up and you see all the characters on the LCD and you get cut off. That won't happen if you don't use a speakerphone, but the speakerphone is one of the reasons to buy this stock. The set has no problem and Fluke doesn't want to fix it. You probably won't be able to find anyone to fix it as Fluke says there's no problem (I found a place to fix it using a couple of older dateplates that were in stock). On the plus side, the butt set is very heavy and very well made. So if you don't mind using the speakerphone, it works very well as a weapon to protect yourself when you're on the phone in a bad area.