Harping back to my own accent, Siri probably does a better job than most humans down South.
Per call centre speech recognition, I find most will recognise things spelled out in Internationally recognised phonetic alphabet “Alpha, Bravo, Charlie, Delta...”. This works well for postcodes, for example, as well as car registrations, etc.
But when I drop into phonetics with most humans, it often just makes things worse. “Hotel, what?”.