I know, due to "meddling by Europe"*, that 112 is mapped to 999.
Not long ago, I was making a call. It answered very quickly, the voice said
'Emergency, which service do you want'. I stuttered and apologised (*), explaining that I had clearly mis-dialled, and the call ended quickly and amicably.
Being a fancy DECT phone it kept a log of dialled numbers so I could see that I had indeed mis-dialled. What I couldn't figure out was why I had been connected to '999' when it didn't even contain these digits, let alone commence with them. Later the penny dropped, I'd probably been 'stung' by one of these pesky mappings.
Also managed once to literally dial 999 by mistake. My employer's PBX employed the usual, dial '9' for an outgoing line. For some reason I didn't think the '9' had worked. So I pressed '9' again, and again, and again...
* My understanding is, if you ever do call Emergency by mistake, always explain - don't just hang up, else they might be left wondering if somebody is in trouble.