"Advanced eavesdropping systems enable virtually all naval platforms to offer some degree of intelligence - gathering, but several navies continue to develop and deploy the sophisticated capabilities that only dedicated vessels can provide. It is now routine for example to fit advanced signals intelligence (SIGINT) gear capable of monitoring and intercepting cell-phone network traffic to a whole raft of vessels, from patrol craft to frigates and submarines. Below the surface, one of the key systems indicative of advanced existing capabilities is Lockheed Martin's BLQ-10 ESM mast integrated into the US Navy's (USN) Sea-wolf, Virginia and Los Angeles-class boats."