... Many top Greek officials, including the Prime Minister, and the U.S. embassy had their mobile phones tapped. What makes this interesting is how it was done: software was installed on the switch that diverted calls to a prepaid phone. Think about who could manage that.
not too hard, actually. softswitching makes this kind of hi jinx relatively easy, and the Cirpack switching system Vodafone uses is commonly available (to those steeped in EU telco at least). [see http://www.cirpack.com/products/hvs.shtml ] i test systems like this from excel/lucent that use a unix host controller communicating with one or more switch chassis full of blades for spans of T1/E1, SS7, etc. they send well defined packets over ethernet to configure switch spans and perform call handling. it's an ugly binary protocol, like most are, but easily manipulated. if you knew what you were doing it would be straightforward to insert a promiscuous device on the LAN or add a process on the unix host used by the softswitch that listened for incoming calls from a given set of MIN's and one way conference these calls to a third party*. if you had access to a current version of the softswitch software itself for modification it would be even easier (most companies license sources and tailor or customize the software to run these switches so it's not quite as simple as a generic drop in replacement). it took "a professional" to do this, sure, but the number of people skilled enough to pull this off is not a small number. * the pre paid phones were probably vodafone as well, so that transit for the conference'd calls was all on the same network and would thus avoid using circuits from other carriers which would need to be accounted for. (that is to say, it would be much easier to hide these conferences as long as they stayed in network, rather than tying up spans to external carriers which would probably trigger accounting discrepancies)