The Standard mode is utilized by the virtual extensions that you develop whenever possible by default. Enhanced signaling mode is a second option that is available to all customers. However, virtual extensions won’t work correctly in this mode unless your PSTN provider supports specific network signaling extensions, and there aren’t very many PSTN providers that do. Enhanced signaling mode is available to all customers.
1 In the admin section of https://admin.webex.com, navigate to the customer view and then choose Services > Call > Service Settings.
2 After selecting Enhanced signaling mode, scroll back up to the Virtual Extensions Mode section and click the Save button.