Unless they frequency-modulate the packets they send home to transmit additional data and you'd probably never figure it out looking at Wireshark output that they are sending more than meets the eye. This is a simple trick; there are probably many other I can't even think of.
I've never heard the term "frequency-modulate" applied to software, and Wikipedia only knows about the radio kind of modulation. Can you please explain what this is?
This is an interesting idea. I assume by "frequency modulation" of data, he means adjusting the timing of the transmissions to create an out-of-band channel that might be more difficult to notice when packet sniffing. As a crude example, if I uploaded War and Peace to you, not as a steady stream of traffic, but as bursts of dots and dashes, I could send "The Magic Words are Squeamish Ossifrage" in Morse code. (Although in the context of apps phoning phone, I'm not sure what the advantage is over simply encrypting the stream...)
