I'm sure the technology exists to detect keywords in phone calls, however I find it unlikely that they can afford to put it on every phone line in the world, much less hire all the people they'd need to listen to the phone calls to filter out the false positives.

I can't see how their technology can do much better of detecting the words "Nuclear bomb" on the phone

Plus also, radio triangulation has nothing to do with keyword listening, it's a much more basic technique and has been used for at least 60 years.

I think they would have found Bin Laden much better from his satellite phone if they hadn't announced to the world's media that that's what they were doing.