Mobile phone code question?

Unless your friend is going to buy an Australian Phone while he's there then no, you won't need to change any of the number you normally dial. All he's doing is going to a different country so his number stays the same. I have friends that have visited all round the world and have never had to change their number unless they bought phones/SIMs from the respective countries. A friend from the UK went to Oz and I dialled his normal UK number. My mate from Canada comes across here and I still have to dial his Canadian number to get hold of him.

yeah you'll need the 61
i learnt that one in bali

hi, I have an uncle in Oz and regularly speak to him, The normal international code is 00 61 then the area code and number, but on mobiles you ignore th e two zeros, also as a thought and it works to you might have to put the add sign (+)before the 61

Just call 853 no.
I believe it's a Macau registered no. instead a Hong Kong one.
Hong Kong zip is 852.