Voice notifications can be enabled, and turned on or off by default, or disabled by facility.
When voice notifications are enabled, you see the option to send voice and/or email notifications when creating or updating an incident. You can choose to have voice notifications on or off by default, but either way, the person creating the incident can see the option and decide whether to send voice notifications to some or all contacts and candidates. When voice notifications are disabled, the option for voice notifications no longer appears and notifications are only sent through email.