Create and configure a Sinch SIP trunk

Connect Sinch Elastic SIP Trunking with LiveKit for inbound and outbound calls. Sinch Elastic SIP Trunking uses static endpoint routing for inbound calls and ACL-based or digest-based authentication for outbound calls.

Prerequisites

The following are required to complete the steps in this guide:

• A Sinch account with Elastic SIP Trunking access.
• A purchased phone number (DID) from Sinch.
• A LiveKit Cloud project.

Create and configure SIP trunk

Complete the following steps to create and configure your SIP trunk.

1. Sign in to the Sinch dashboard.
2. Select Voice → Elastic SIP Trunking → Trunks.
3. Select Create new SIP trunk.
4. Complete the SIP trunk Name and Domain name fields.
5. Select Create Trunk.

Continue with the following sections to set up inbound and outbound calling.

Inbound call settings

Add a static endpoint to your Elastic SIP Trunking trunk that routes inbound calls to your LiveKit SIP endpoint.

1. Sign in to the Sinch dashboard.

2. Select Elastic SIP Trunking → Trunks and select your trunk.

3. In the SIP Endpoints section, select Add an Endpoint.

4. Enter a Name for the endpoint. For example, "My LiveKit endpoint."

5. For IP Address/FQDN, enter your LiveKit SIP endpoint. For example, vjnxecm0tjk.sip.livekit.cloud.

   Region-based endpoints

   To restrict calls to a specific region, replace your global LiveKit SIP endpoint with a region-based endpoint.

6. For Port, enter 5060.

7. For Protocol, select TCP.

   Secure trunking

   If you're setting up secure trunking, use port 5061 and protocol TLS instead.

8. Select Create.

Outbound call settings

Sinch Elastic SIP Trunking supports IP-based ACL authentication and digest-based authentication for outbound calls. Configure your preferred method in the Sinch dashboard:

1. Sign in to the Sinch dashboard.

2. Select Elastic SIP Trunking → Trunks and select your trunk.

3. In the Outbound call settings section, configure the authentication method for outbound calls:

   • ACL-based: Add an ACL entry for the LiveKit Cloud IP ranges.
   • Digest-based: Set up a username and password for SIP digest authentication.
   Note

   For LiveKit Cloud IP ranges, check your project settings or contact LiveKit support.

Assign a phone number to the trunk

In the Phone numbers section, select Assign Numbers and select the phone number you want to assign to the trunk.

Next steps: LiveKit setup

Finish connecting your SIP trunk to LiveKit using the main setup documentation.

Troubleshooting

If calls fail to connect, check the following common issues.

Inbound calls don't reach LiveKit

• Verify the static endpoint in your Sinch trunk points to the correct LiveKit SIP endpoint and port. See Inbound call settings for more information.
• Confirm the phone number is assigned to the trunk. See Assign a phone number to the trunk for more information.
• Check that the endpoint hasn't been recently changed. Allow at least 60 seconds for changes to propagate.

Outbound calls fail

• Verify the authentication method and configuration. If using ACL-based auth, confirm the ACL includes the correct LiveKit Cloud IP addresses. If using digest auth, verify the username and password credentials match. See Outbound call settings for more information.
• Check that the caller ID is in E.164 format and that the phone number is assigned to your Sinch trunk. See Assign a phone number to the trunk for more information.

One-way audio

One-way audio is typically caused by NAT or firewall issues affecting RTP media. Verify your Sinch trunk configuration allows bidirectional media. See Elastic SIP Trunking test plan.

Additional troubleshooting

For additional troubleshooting help, see the SIP troubleshooting guide and the Sinch Elastic SIP Trunking integration guide.

Additional resources

The following guide provides validation instructions for Sinch Elastic SIP Trunking.

Sinch Elastic SIP Trunking test plan

Validation steps for your Sinch Elastic SIP Trunking inbound and outbound setup.