What a Carrier Trunk Is in VICIdial

If you are new to VICIdial, the word "trunk" trips a lot of people up. A trunk is just the connection your dialer uses to reach the outside phone network. Without one, your agents can log in, your campaigns can load leads, and absolutely nothing will dial. The trunk is the door between your server and everyone you want to call.

In VICIdial that door is configured as a Server Carrier entry. A Carrier is the company that actually carries your calls onto the public telephone network, and a Trunk is the configured link to that company. This post walks through what a carrier trunk is, the pieces that make one up, and how a call travels through it. It does not cover the click-by-click setup; for that, see how to add a new carrier trunk.

A trunk is a connection, not a phone number

People often confuse a trunk with a phone number. They are different things. A trunk is the pipe; a DID (direct inward dialing) (the actual number people dial to reach you) rides over that pipe. One trunk can carry many numbers, and it carries calls in both directions: outbound calls your dialer places, and inbound calls arriving from the phone network.

VICIdial supports trunks over SIP (Session Initiation Protocol) (Session Initiation Protocol, the most common VoIP signaling standard) and IAX2 (Asterisk's own Inter-Asterisk eXchange protocol). It does not auto-configure physical T1, E1, or analog telco lines; those need extra hardware and manual setup. For nearly everyone running a software dialer today, the trunk is a SIP trunk pointed at a VoIP provider.

The four fields that define a trunk

When you look at a Server Carrier record in VICIdial, four fields do most of the work. Each one is worth its own post, but here is the short version of what each does:

• Registration String — tells your server how to announce itself to the carrier so the carrier knows where to send your calls. Optional for some providers.
• Account Entry — the block defining the peer: the carrier's host, your username and secret, and which codecs and contexts to use.
• Dialplan Entry — the routing rules that match an outbound number and send it out this trunk.
• Server IP — which dialer server this trunk record belongs to.

The Account Entry creates what Asterisk calls a SIP peer — a defined relationship between your server and the carrier. The Registration String is covered in the registration string post, and the Dialplan rules are the subject of their own deep dive.

How a call flows through the trunk

When a campaign places a call, VICIdial hands the number to the dialplan. The dialplan matches a pattern, logs the call, then dials it out through the trunk's peer to the carrier. The carrier puts the call onto the phone network and connects you to the person on the other end. Inbound calls run the same route in reverse: the carrier delivers the call to your trunk, and the trunk's context routes it where you tell it to go.

flowchart LR
  A[VICIdial campaign] --> B[Dialplan match]
  B --> C[Account Entry peer]
  C --> D[Carrier]
  D --> E[Phone network]
  F[Inbound call] --> D
  D --> G[trunkinbound context]
  G --> H[Ingroup or agent]

Why you bring your own trunk

On VICIfast you run your own dialer and bring your own carrier. We do not sell minutes or resell carrier service, so you keep your rates, your numbers, and your relationship with the provider you choose. Picking a good provider matters more than the config; see our guide on choosing a SIP carrier before you sign anything.

Once you understand the trunk as a connection with four defining fields, the rest of carrier setup stops feeling like guesswork. Read the carrier integration guide for the full picture, then spin up a server. VICIfast provisions a secured VICIdial box in under 40 seconds, so you can have a trunk wired and dialing the same afternoon. See pricing to get started.