In order to send voice messages to selected users all at once, make sure the owner of the PDL is the subscriber account and not any other account such as the Unity installer account. If it is another account, change it back to the subscriber account of the user who wants to send the mass message.
Complete these steps in order to push the mass voice message:
Press the Messages button on your IP phone.
Enter your password.
Press 2 (Send a message 2).
Spell the name of the person or distribution list.