Quite probably the communication devices were manufactured correctly.
Some hypothesised that along the supply change the devices had been ‘armed’.
Another xplanation is that short circuits were triggered remotely. Which would cause the devices to burn and/or explode. The batteries are sealed components with facilitates a pressure build up. Batteries are made from reactive components. The integrated circuits are susceptible to short circuiting. So how to ‘excite or overload’ the circuitry. Using interference, vibration, excessive switching, etc. … that can trigger just enough heat to cause the shorting in the tiny integrated circuits. If this is the case, then not only pagers and radios can be targeted, but other devices as well.
Often pagers, radios and mobiles are positioned in close vicinity to the carrier’s private body parts, and when called, the devices are positioned to the head region for reading, listening and/or speaking. So detonations can reach both heads of the targeted Hizzibillies or Mullahians.