Are you claiming that these sources are wrong, and Hezbollah actually bought them from some retailer who happened to have 5,000 units of tampered inventory?

So, you're suggesting instead that a paramilitary group picked up their phone, called a company in Taiwan (I guess there's a taiwanese-arab translating terrorist branch), told them "Hello, I'm Hezbollah, Yes, I need 5000 pagers because...reasons, take my money", nobody batted an eyelid starting from payment processors (I can only imagine they used Bison Dollars from Street Fighter The Movie), to shipping and logistics from several countries.

Then, finally, they made a big long queue of all Hezbollah members and gave each of them one of 5000 pagers, all while saying "remember, never give this extremely common consumer device to no one else for at least five months!"

Instead of, you know, buying them locally from friendly wholesale resellers when new units were needed. (remember, it's radio and pagers we're talking about. Not guns. Not Missiles. It's basically stationery.)

I'm tempted to end this with some snarky conclusion, but I'd say no further comment is really needed.

I suppose the source could be lying, but what is your alternate theory exactly? Militaries don't tend to procure their communications equipment from the shelves of Radio Shack. Lebanon doesn't have a booming pager market, so it's unlikely that some local distributor just happened to have 5,000+ pagers sitting around.

This was clearly a special order (which doesn't mean no distributor was involved), and Occam's razor suggests that Mossad tampered with that particular order, rather than tampering with random pagers and just hoping that some of them might end up being purchased by Hezbollah later.