To set your outbound number, simply select Settings > Phone > Outbound default and select the number that should be the default number for the organization.

The selected phone number will be the default outbound number when the Dixa interface is reloaded.

Select the default phone number for your organization from the drop-down list under  Outbound default. settings saved-zgw.png

Agents can also select a default outbound number. The agent default number overrides the organization default number. Find out how, here.