> ## Documentation Index
> Fetch the complete documentation index at: https://docs.astradial.com/llms.txt
> Use this file to discover all available pages before exploring further.

# SIP trunks

> How to configure SIP trunks in Astradial to connect to phone carriers for making and receiving calls.

A **SIP trunk** is the connection between Astradial and a phone carrier (like Tata, Airtel, Twilio, or any SIP provider). Without a trunk, you can make calls between extensions inside Astradial, but you cannot call real phone numbers or receive calls from the outside world.

## What is a SIP trunk?

Think of a SIP trunk like a phone line connecting your office phone system to the telephone network. It is the bridge between your internet-based phone system and the real phone network.

| Term               | Meaning                                              |
| ------------------ | ---------------------------------------------------- |
| **Inbound trunk**  | Receives calls from the phone network into Astradial |
| **Outbound trunk** | Sends calls from Astradial out to phone numbers      |
| **Peer-to-peer**   | Both inbound and outbound on the same connection     |

## View your trunks

Go to **Trunks** in the sidebar under **Deploy**. You will see a table showing all configured trunks with:

* **Name** — A label you gave the trunk
* **Host** — The SIP server address and port
* **Type** — Inbound, Outbound, or Peer-to-peer
* **Transport** — UDP, TCP, or TLS
* **Channels** — Maximum simultaneous calls allowed
* **Registration** — Whether the trunk is successfully connected to the carrier
* **Status** — Active or Inactive

## Create a trunk

<Note>
  Only admins and owners can create trunks.
</Note>

<Steps>
  <Step title="Click Add Trunk">
    Click the **Add Trunk** button (plus icon). Only visible to admins.
  </Step>

  <Step title="Fill in the connection details">
    | Field            | What to enter                      | Example          |
    | ---------------- | ---------------------------------- | ---------------- |
    | **Name**         | A label for this trunk             | Tata SIP         |
    | **Host**         | The carrier's SIP server address   | sip.provider.com |
    | **Port**         | SIP port (usually 5060)            | 5060             |
    | **Transport**    | UDP, TCP, or TLS                   | UDP              |
    | **Type**         | Inbound, Outbound, or Peer-to-Peer | Outbound         |
    | **Username**     | SIP authentication username        | your\_sip\_user  |
    | **Password**     | SIP authentication password        | your\_sip\_pass  |
    | **Max Channels** | How many simultaneous calls        | 10               |
  </Step>

  <Step title="Click Create">
    Astradial creates the trunk and registers it with the carrier. Check the **Registration** column — it should show "registered" within a few seconds.
  </Step>
</Steps>

## Registration status

| Status           | Meaning                                                               |
| ---------------- | --------------------------------------------------------------------- |
| **Registered**   | The trunk is connected and ready for calls                            |
| **Unregistered** | The trunk is not connected — check credentials or network             |
| **Failed**       | The registration attempt failed — verify host, username, and password |

## Edit a trunk

1. Click the three-dot menu next to the trunk
2. Click **Edit**
3. Update any field (leave password blank to keep the current one)
4. Click **Save**

## Delete a trunk

1. Click the three-dot menu next to the trunk
2. Click **Delete**
3. Confirm the deletion

<Warning>
  Deleting a trunk disconnects all phone numbers that use it. Make sure to reassign your phone numbers to a different trunk first.
</Warning>

## Get a free developer trunk

If you need a trunk for testing, click the **Request Free Trunk** button at the bottom of the page. This sends an email to the Astradial team to set up a free developer trunk with 1 channel and 1 Indian DID for 30 days.