How to text a number in Japan, from Australia? -

I want to text my friend who s in Tokyo, Japan. I m in Australia and I want to text from my mobile to her mobile. Say her number is 08058750474, what alterations should I make to her number so that the text will go through? I hear you have to put a + in front of the number first? Thanks in advance.

I think it is+02. I m not really that sure cos it had been months since i went to japan so i cant really remember very clearly.