Telephone numbers in Polish - what pronunciation?

Could someone please tell me the usual form for saying telephone numbers in Polish?

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).

I'm a teacher of English as a second language. Sorry, Polish is not one of my languages so please answer in English.

Dziękuję! (I'm trying..!)

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.

In central Poland we use the same method as in Kraków.