Drop a call?On to?Meaning? My friend Eric Ripert has never been to mainland China. And due, perhaps, to his adherence to the teachings of Tibetan Buddhism—and a friendship with Richard Gere—he had concerns about what kind of a welcome he’d receive. For the first few nights, he slept with a tin foil helmet around his head, convinced, (every time his cell phone dropped a call that “they” were on to him). I assured him repeatedly that he was the very last person any Chinese secret services would give a shit about, but he was unconvinced. Nonetheless, his paranoia was acute. What does the sentence in brackets mean? Thank you.