Each "Contact" can have multiple "Connections" (i.e. one Voice connection, one Mobile connection, etc.).

Click on an existing contact (or add a new Contact if none exist) and click "Configure Contact" then "Add New Connection" to add another connection type, a Voice connection in this case.

Fill in required fields. Select ACK, Schedule and Format options.

Additional options such as "Override Gateway Audio Settings" can be utilized if desired. This option allows certain contacts to have custom audio settings with different volume and speech rates, just for them. 

The optional check box for "Require additional Caller-ID authentication" changes inbound call behavior in the following manner:

If the box is checked - The number calling inbound into WIN-911 for alarm data MUST be the same phone number and use the correct authorization code configured here.

If the box is NOT checked - The number calling inbound into WIN-911 for alarm data can be any phone number from any device, as long as the authorization code is correct, it will be successfully connected.

And always... Save your changes!