The Inbox has two entry points.
Org-wide Inbox (main nav)
Sign in and open Inbox from the sidebar. The nav item shows an unread badge counting all unread conversations across every channel.
Per-customer Inbox tab
On any customer profile, the second top-level tab is Inbox (Overview · Inbox · Contacts · Sites · …). It shows only that customer's conversations, with the same channel filters and the same composer.
If you're used to the old location
The Communication Log used to live inside the Activity tab. It was promoted to its own top-level Inbox tab so it isn't buried. Deep links pointing at `?subtab=communication` auto-redirect to the new tab.