| AVP | No. | Usage |
| User-Name | 1 | SIP URI for our end of the call leg |
| Callback-ID | 20 | SIP URI for other end of the call leg |
| Called-Station-Id | 30 | Dialled number as received |
| Calling-Station-Id | 31 | Calling number as received |
| Acct-Status-Type | 40 | 3 Interim |
| Acct-Session-Id | 44 | Unique ID for session |
| Acct-Multi-Session-Id | 50 | SIP Call ID for call leg, and second instance is Session-Id of linked call |
| Acct-Event-Timestamp | 55 | Time call answered |
| NAS-Identifier | 32 | Configured hostname of FireBrick |
| NAS-IP-Address | 4 | Far end IPv4 address for SIP if using IPv4 |
| NAS-IPv6-Address | 95 | Far end IPv6 address for SIP if using IPv6 |
| NAS-Port | 5 | Far end UDP port for SIP |
