Trust me, the GB know to hang up once they are asked questions as mentioned Jonathan. They know a person would be recording it if they went through the trouble to ask them the questions.
It it doesn't stop them in person (conventions, bethel meetings, yearly meeting, zone visit) and if we are going to credit them with being smart enough to know they are being recorded on the phone then surely they know they are being recorded at these events. Yet they keep showing their true colors and saying insane things. To imagine him talking to a confused bethelite or brother saying lying is okay if it's theocratic warfare is no stretch, especially since a previous comment explained why he even picked up the phone to begin with. (It likely appears to come from within bethel)