A Cloud Voice seat is usable without extras. The add-ons are for recording, a receptionist console, fax, and desktop integrations.
Already on the seat
Every seat includes an auto attendant, hunt groups, the Webex app, and Go Integrator Lite. You do not add those again.
Optional extras
The order can add hosted SIP voicemail, fax to email, call recording with 180 days of storage, and long-retention recording charged per gigabyte for 7 years.
Call Centre ACD is the queuing feature, and one is required per site that uses queues. Receptionist Enterprise is a receptionist console licence for that site. Go Integrator DB is a database screen-pop. Go TAPI is the integration for desktop softphones.
How they are billed
Add-ons are monthly and ex VAT. The price is on the order. A broadband order can hold up to three of them. They can be left off and arranged later.