The UK has (essentially) one PSAP for the whole country (it's not actually — there's a number spread across the country for reasons of redundancy, but call allocations are done across the whole network).

It has a few interesting results — most notably, when giving a location, they likely know nothing about it. If you say you're in "Central Park, Fakesville", and it's a small park where you can see the whole thing from the entrance, they will still ask you where about in the park you are — because they don't know. People in high-stress situations can end up wasting time trying to describe in gratuitous detail where they are, instead of just giving an answer like, "it's small; they'll see".

I'm surprised that the situation wasn't handled better by the phones, though. At least here, if a mobile can contact any tower (regardless of network), an emergency call can be placed through it without charge. I suppose if the emergency line is already stagnated, trying again on a different network would just make it worse. Hmm…