Old cellphones, in my household ...

Take care with old phones as kid's toys. Even if they do not include service, they will still have the capability to dial 911 and the emergency services will disapprove of your children calling them with no reason...

They get separated from their batteries. Batteries and devices get put in separate Tupperware bins, and every year or so the bins are taken to the local recycling center. After that I expect they wind up in the Far East where child labourers get poisoned as they disassemble them.

for when newer devices get damaged/broken/lost

I want to be responsible environmentally, so I hold onto our old phones with the intent of recycling them.

In practice, though, what it's meant is we still have cell phones from the late 1990s in a box on the shelf.