Re: Talyrand: they forgot nothing and learned nothing!
Your biggest problem isn't 5-7, it's just 5. Spies can always place calls from public areas without CCTV, well not very easily but we'll come back to that, but where will their recipients be? The person receiving the call won't know they need to receive a call, so they'll be wherever they were before, which is potentially exposing. They will have to keep their burner phone turned on to receive said calls, meaning it will be able to track their location if someone ever identifies that phone as a device of interest. If you were planning that the conversations are always preplanned, so both ends can go to a public place, how does spy A indicate to spy B that spy A has urgent information that spy B needs to know when they don't have a scheduled meeting for several days?
Now, a public place to make a call without surveillance cameras. I really hope no spies ever go to London or most cities really. There are cameras everywhere. If you find a place without cameras, someone could check feeds for the cameras near the place to find the person who spent the right amount of time in that place before leaving. The other problem is that, if you make a call in public, you have to say all your secret stuff in public. People can hear your conversation which either includes incriminating things or cryptic things, which might cause your listener to report you or listen in.
Biting the hand that feeds IT
