I'm not sure what you're even on about, if the pagers (in your view) don't qualify as 'booby traps', they'd still fit the description of 'other devices' that are in the same restriction:

3. "Other devices" means manually-emplaced munitions and devices designed to kill, injure or damage and which are actuated by remote control or automatically after a lapse of time.

I personally think their being disguised as civilian objects is of particular note and makes the offence more severe, but even without that classification it's considered a war crime

1. This Article applies to: (a) mines (b) booby-traps; and ( c) other devices.

2. It is prohibited in all circumstances to direct weapons to which this Article applies, either in offence, defence or by way of reprisals, against the civilian population as such or against individual civilians.

3. The indiscriminate use of weapons to which this Article applies is prohibited. Indiscriminate use is any placement of such weapons:

(a) which is not on, or directed against, a military objective; or

It would be a tall order to prove that the pagers were actually and exclusively distributed to Hezbollah combatants

(b) which employs a method or means of delivery which cannot be directed at a specific military objective; or

As with above, they had no reasonable way of knowing that the pagers would be directed as intended or be on their intended target at the time of discharge

( c) which may be expected to cause incidental loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof, which would be excessive in relation to the concrete and direct military advantage anticipated.

Pretty clearly caused incidental loss of civilian life and injury, especially in relation to the concrete military advantage. I haven't even heard stated any material military advantage gained from this other than relating to the fear they intended to evoke

4. All feasible precautions shall be taken to protect civilians from the effects of weapons to which this Article applies. Feasible precautions are those precautions which are practicable or practically possible taking into account all circumstances ruling at the time, including humanitarian and military considerations.

No matter how you're slicing it, under Protocol II of the UN the pager attacks would be a violation and subject to war crime charges. It being a literal 'booby trap', 'mine', or 'other device' is immaterial to its criminality.