Trunks
A trunk is a SIP connection to another PBX (for example a NEC system) or to a carrier. Trunks are managed on Trunks; the edit dialog is split into tabs.
| Tab | Settings |
|---|---|
| Basic | System name, title, IP/host, port, transport, codecs, outbound proxy, extra matched hosts |
| Authentication | IP-based or registration mode, username/password, registration timers |
| Caller ID | Outbound caller ID, From user/domain, send name, PAI / RPID headers |
| Media & Fax | DTMF mode, T.38 options, fax detection |
| Network & NAT | Qualify interval, direct media, RTP symmetric, rewrite contact, force rport, session timers |
| Routing | Context, channel limit, inbound DID normalization, transit routing, outbound caller ID normalization |
| Advanced | Extra PJSIP parameters, one per line |
Identification
Calls from a trunk are recognised by source IP (the trunk address plus matched hosts). Two trunks must not share an address: a call would match both. Change the IP when you copy a trunk.
Inbound DID normalization
Keep only the last N digits of the DID trims the called number before it is matched against inbound routes, e.g. 4 turns 03704187840 into 7840. 0 keeps the full number.
Trimming applies to every call from the trunk. If the trunk also sends transit calls (below), trimming cuts those numbers too — 4440478 becomes 0478. Use it only when the trunk sends nothing but DIDs; otherwise define the inbound routes with the full numbers the trunk sends.
Transit routing
Allow outbound routing lets calls arriving on this trunk use the outbound routes of the selected route group and reach local extensions. A NEC system can then send external calls out through the carrier trunk via AiPBX. Without it, only inbound routes are available to the trunk.
Outbound caller ID normalization
Applied to the caller number of every call leaving through this trunk:
- Keep only the last N digits (
0= the whole number) - Prepend a prefix
Example — main number 903704187000, extension 7840 on a NEC system calling out: keep 4, prepend 90370418 → the carrier receives 903704187840.
When a route falls back to the next trunk, the original caller number is restored first, so each trunk applies its own rule to the original number.
Renaming, copying, ordering
- The system name can be changed after creation. The old PJSIP objects are removed, outbound routes that use the trunk are updated, and the dialplan is marked for Apply. Old CDRs keep the old name.
- Copy creates a new trunk with the same settings (see Portal basics).
- Order the list by dragging; the first active trunk is the primary trunk.