Gen III Hands-Free/Continuous Tone

I have a 2010 Prius III with Nav and am a little frustrated with some of the Hands-Free features. For example, I want to be able to access my voicemail which requires the transmission of a continuous tone after the call connection is made. I have added the w### at the end of the phone number in the phonebook registration. It works just fine when not in hands-free mode;the call connection is made, and when I press 0-9, the code is visible along with the SEND and MUTE buttons. But when I am using voice commands in hands-free mode, the system behaves as if the tone information does not exist. The code does not appear after hitting 0-9 and no SEND button is visible. My Motorola RAZR V3 is supposed to be adequately compatible, according to "letstalk."