I found this to be a very interesting article on ISIS with insights to their communications,<p><a href="http:&#x2F;&#x2F;www.theguardian.com&#x2F;world&#x2F;2014&#x2F;dec&#x2F;11&#x2F;-sp-isis-the-inside-story" rel="nofollow">http:&#x2F;&#x2F;www.theguardian.com&#x2F;world&#x2F;2014&#x2F;dec&#x2F;11&#x2F;-sp-isis-the-in...</a><p>When people left Bucca, they had written each other&#x27;s names &amp; numbers on the elastic of their underwear.<p>They also responded to Anonymous&#x27; threat toward ISIS by suggesting techniques to secure Comms and what to avoid.<p><a href="http:&#x2F;&#x2F;www.businessinsider.com.au&#x2F;isis-anonymous-statement-2015-11" rel="nofollow">http:&#x2F;&#x2F;www.businessinsider.com.au&#x2F;isis-anonymous-statement-2...</a><p>I would suggest that this cell did not use protection but I am confident the larger ISIS network is not so transparent.  My suspicions would be that most Comms is via word of mouth.