Documents and paths
Configuration is a set of documents, not a directory layout — and the one rule about relative paths that catches everybody.
Tenants
The Tenant document — domains, DIDs, caller ID, timezone and music on hold — and the documents that live inside one.
Accounts and extensions
SIP credentials, extension numbers, registration and what happens when several devices share one extension.
Trunks
Connecting to a carrier — registration, caller ID, and how inbound source addresses are discovered.