How did pagers explode?

Part of being associated with a university is making yourself available for expert commentary. Yesterday I had a request from SBS News to talk about exploding pagers. I could have said "No, I am on holidays". But instead I propped my phone up on a suitcase and was interviewed for a segment six minutes into the national nightly news: "How did Hezbollah's pagers explode in Lebanon and Syria?".

As it happens, when working at HQ Australian Defence Force in the eatly 1990s, I tested the use of a pager, while travelling around defence bases in northern Australia by RAAF aircraft. The units were able to receive messages in remote areas and while in flight, making them useful.

One feature which I noticed was that it was possible to send a test message to a pager which was apparently switched off. The only way to prevent this was to remove the battery from the unit. I suggested it is likely that something like this was used for activating a few grams of explosive hidden in the pagers. Also I warned that some of the pagers could have not been delivered to their intended targets and pose a danger to the community, worldwide.