Just the not-quite-100%-reliable nature of VoIP. It's hard to know exactly what you are describing as "strange clicking" but many things like jitter or silence suppression (whether on your end or the other party's) could be responsible. Realistically, if somebody were willing and able to eavesdrop on a VoIP call, they'd do by capturing your media streams without actually joining. In other words, you'd never hear ANYTHING because the eavesdropper wouldn't be injecting any audio at all. The exception would be if you've connected your OBi to the old POTS wiring of your home or office, in order to drive multiple phones in various rooms. In that case, somebody in another room could pick up their phone to listen in, just like they would have in the old days, because the call is only VoIP up to the point of your OBi. Coming out of the OBi, it's POTS. That's the point of an ATA: to connect VoIP to POTS. If you have a spy inside your own home or office, that's your problem to deal with.
The random activation of Call Recording was a long-standing Google Voice problem. It's because their DTMF detection erroneously thinks it hears you press 4 sometimes, even though you didn't. That's why there is now a specific checkbox in Options to disable the Call Recording feature. If you go back to old postings in the Google Voice support forums, you'll see literally thousands of complaints about it, from before they added the checkbox to disable it. I personally had it happen to me at least 2 dozen times. After checking the box, not once.
