Setting up seller account. Int. mobile number used but no pin rcv'd. how change to OZ number?

[au_walto]

I want to set up a seller account.  In the authentication process it asks for a phone number and I enter my international phone number.  No pin was received.  I want to change to an Australian phone number for pin verification but cannot see where this can be done.  You never seem to be able to get back to that page?  Please advise