Well here in Australia our emergency number is 000 (which was the worst by the way since when everyone had desk landline phones curious toddlers would stand on their tippy-toes trying to reach the phone on the desk and would always mash 000 since it was the only number they could reach) but if a US citizen is here and needs emergency services and just instinctively dials 911 it will redirect to 000.
So tl;dr I think any emergency number will just redirect to the country you are in. I could be completely wrong as I’m just basing it on what happens in Australia.
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