How can you change your voicemail message? with a sony ericsson k800i optus prepaid phone.?

i've called 321, i just don't which numbers to press to get to where i need to go to change my voicemailHow can you change your voicemail message? with a sony ericsson k800i optus prepaid phone.?yer im in same boat with you with my sony ericsson k800i on optus. it nothing to do with the phone it all gotta do with optus, i just went though the menu and it driving me insane but i finaly figure it out.call 321 then click 8 then click on 4, click on 4 then click on 1 and follow the prompts and it will work.