NASA also used to coordinate telephone-based contact (maybe they still do? not sure). They'd simply patch the phone call in to radio equipment that they acquired and operated for this purpose. Confirmed beforehand out of personal interest though: it was still over the ham bands.
Something really amazing happens when kids are given an opportunity to experience something like that: science goes from being a largely theoretical exercise to having some amount of practical applicability. The kids that got to actually _talk_ on the radio were incredibly curious and eager to learn as much as they could about everything. They wanted to know how radio works. They wanted to know more about orbital mechanics and how we know where to point the antenna (to the point of actually _asking_ to learn the math). They wanted to know how big the ISS was and how we even got it to orbit (which led to some model rocketry-related topics).
I imagine that it was very difficult to justify the expense of acquiring and transporting heavy amateur radio equipment to the space station (even if you're just thinking about the cost of putting the equipment into orbit - the cost is (pardon the pun) astronomical), but this kind of stuff _matters_. Making science accessible to children in a way that isn't just preparing them for the next standardized test _matters_.