The only way this would work is if you have either Bluetooth phone prep with SES (Voice Recognition) active, or you have the discreet SES module. Otherwise, as you've found, pressing the 'talking man' button just brings up the tel dialling options. You do have to press and HOLD the button though, and wait for the beep. No beep, no SES!

Do you have Assist (to get the phone options) or do you actually have Bluetooth Phone Prep? If the latter, then it's very easy to code for Voice Recognition with NavCoder and a suitable i-bus interface.