Many posts ago somebody stated that their cell phone had received three texts welcoming them to a country that the aircraft they were in had transited at FL330
If this occurred it would have required a “handshake” signal exchange between the phone and mobile network operator.
I can’t help wondering if those coordinating the SAR effort have considered cross referencing the mobile phone numbers of all on board with every cellular network that flight MH370 could conceivably have over flown?