That is, is each digit said in isolation, as we do in English (eg 617345...six-one-seven-three-four-five).. or is the 'paired' form used? (eg sixty one - seventy three -forty five).
No isolated numbers. We use tens and hundreds. A typical Krakow number: 012 -647-25-37.
zero twelve - six hundred and forty seven - twenty five - thirty seven.
zero dwanaście- sześćset czterdzieści siedem - dwadzieścia pięć - trzydzieści siedem.
However, I always say my numbers with isolated digits because it is easier. People are sometimes surprised hearing me.