Wirelessly posted (iPhone: Mozilla/5.0 (iPhone; U; CPU iPhone OS 2_1 like Mac OS X; en-us) AppleWebKit/525.18.1 (KHTML, like Gecko) Version/3.1.1 Mobile/5F136 Safari/525.20)
Sometimes it takes it a little while to actually download the message from AT&T so that it will display in visual voicemail. 5 minutes isn't uncommon for me.