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The spooky part is this: They get a trace on the cell phones because they are in use in the Taj Hotel. Then they appeal to various countries to get the full trace back to the source. The calls are VoIP, so they are more like tracing email than like tracing analog or packet switched phone calls on phone lines or satellites. So the investigation proceeds, and they release a dossier that includes phone calls of the terrorists telling the mentors that they screwed up. The screw up, and the phone call about it, comes when they failed to scuttle the fishing trawler they had pirated.
Only the fishing trawler is at least hours, possibly days before they are intercepted at the hotel. So the transcripts contain data that was recorded by one or more of the governments involved, before they suspected the phone number.
Can you say database?