| Access Control Field | Description |
| Access this server | Who may access this server using Passthru. Blank list allows no one. |
| Route through | Who may use Passthru to route through this server. Blank list allows no one. An asterisk (*) allows anyone, without authentication. |
| Cause calling | Who (often server names) may instruct this server to place a phone call to another server to build a route. Blank list allows no one. An asterisk (*) allows anyone, without authentication. |
| Destinations allowed | Destinations to which a server may route clients. Blank list allows all. |
