I would imagine that foreign terrorists would speak in their native language. Any sophisticated terrorist would use code-words (Get on the train and trigger the Goat). Does the system pick up if you spell out a word?
It's certainly possible but there's not much reason why the phone calls would consistently drop unless that was their method of preventing terrorist activity.
It's known that all calls around the president are monitored for X miles, so the technology is certainly in place and in use.
For example, what he describes could be a bug on the "engage phone tracking when keyword is heard".
It's probably been fixed by now if it was a bug such as that. I'm sure bugs like this go unnoticed every day by people interacting with computer systems and just brush it off as a "glitch" or "service issue".
Which incidentally works very differently to the way most people seem to imagine phone tapping works -- some agents in trenchcoats in a dark room full of reel-to-reel tape recorders, wearing headphones and carefully putting crocodile clips onto a particular wire, and listening in, hoping the suspect isn't tipped off by crackles or beeps on the wire, or suspicious dropped calls. Maybe in 1950s Hollywood that was how it worked, but now the NSA is just grabbing the content and metadata wholesale from a backbone connection, and analysing at their leisure.
It's also not how the phone system works.
And if this one is blanked out, too, then you know I'm the newest addition to the Watchlist.
The word was "bomb".
(...Now that I think about it, I was at a train station. Not a major one though, doubt if that's related.)
The same exact thing has happened during phone conversations I've had except with a different word. And I first noticed it years ago but it was post-9/11. When it happened I thought the phone call dropped by accident. I called back and picked up where I left off telling the same story. At the same word the call dropped again. I called back again and said "uhh, that was weird. Did you notice it cut off again when I said _______?" And the call dropped once more. At that point there was no plausible way it was a coincidence. The next time I called, I decided not to test it again.
I've been looking out ever since for some mention of this somewhere. Never saw one until now.