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
Only admins and owners can create trunks.
Click Add Trunk
Click the Add Trunk button (plus icon). Only visible to admins.
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 |
Click Create
Astradial creates the trunk and registers it with the carrier. Check the Registration column — it should show “registered” within a few seconds.
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
- Click the three-dot menu next to the trunk
- Click Edit
- Update any field (leave password blank to keep the current one)
- Click Save
Delete a trunk
- Click the three-dot menu next to the trunk
- Click Delete
- Confirm the deletion
Deleting a trunk disconnects all phone numbers that use it. Make sure to reassign your phone numbers to a different trunk first.
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. 
