How is this a law violation? You can listen in on a call quite easily. Once, with a co-worker, we tried to solve a problem with a subsidiary of a major corporation. The manager we wanted was out, as was his manager, as was his manager, as was his, ...until, finally, mirabile dictu, we were talking to the CEO of the whole corporation (yes, we were "pissed"). Throughout the whole series, not one of the other parties knew I was on the call; my co-workeer did all the talking - yet I was available to testify to anything they said.
Now, did I violate the law? We never denied there was anyone else on the call?
Can't anyone do this? With a Mother Theresa type on call with a notepad?