In your speed dial list is an automatic Voicemail in slot 1. Press and hold, enter *86, (space) password numbers# (pound sign) ... save.
The comma and space allows a break in the dialing, long enough for the call to be answered. Then the password numbers break into the voice asking for it. You're good to go.
Not sure how to get this info into the voicemail icon on the dial pad, but if you just press and hold the "1" on the dial pad after you set it up, it works.