Starting from UCM 6.0, the User facing features (such as CFA, hunt login / logout, extension mobility, DND, etc) can be changed while the publisher is down. However you can only make the changes from the phone, but NOT the UCM admin page or UCM user page.
Take CFA as an example. When the publisher is down, users can update CFA on their phones, but not from the CCM user portal. Admin can't change it from the CCMAdmin page too. All web based UCM admin and user updates must be done on the publisher.
Although the above is the expected behaviour, in my lab I can configure CFA for my phone on the self-service portal (CCMUser page) when the publisher is down. However I can't cancel the CFA from the web self-service portal. Hope this is only an issue specific to my lab as it doesn't make any sense to me. The CFA activate and cancel works perfectly on the phone though, while the pub is down.