Mobile phone gives more security?
It is relatively straightforward to get a 3rd party mule to carry your data in all innocence.
The obvious media would be encrypted USB sticks or SD cards.
However these are usually relatively straightforward to attack by brute forcing.
From the article it seems that a phone (or some variants) can give an additional wrapper. You have to compromise the phone before you can even see the data to attack.
This avoids all the issues of call, SMS, and data recording. Just have a friend of a friend take a mobile phone to the destination to be passed on to the friend of a friend. This does of course cause the innocent mule all sorts of problems so to my mind it is mainly a deterrent to people carrying things they cannot unlock through customs. No chance of getting the data but much publicity about not being duped into carrying stuff. Standard question at check in to include "do you own all electronic devices and can you unlock them if requested".
Oh, and if we are punting ways to encrypt data, how about using a computer controlled sewing machine to embroider information into your underwear? Waistband of your boxer shorts or your bra strap for example? War and Peace might take a while and be obvious but code words, encryption keys and passwords would work. Hold on, I may have just invented an alternative password vault. Password, Officer? Just bear with me a minute <zip>.