Twilio Configuration

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Prerequisites

• An active Twilio account
• A Twilio phone number
• Access to the Twilio console

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Step 1: Create a SIP Trunk in Twilio

1. Log in to the Twilio Console
2. Search for SIP Trunk in the search bar
3. Click Create new SIP Trunk
4. Give your trunk a name (e.g., “Rounded-Trunk”)

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Step 2: Configure Origination

1. In your SIP Trunk, go to the Origination tab
2. Click Add new Origination URI

3. Configure:
   • SIP URI: sip:sip.callrounded.com;transport=tcp
   • Priority: 10
   • Weight: 10

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Step 3: Configure Termination

1. Go to the Termination tab
2. Note the displayed Termination URI (e.g., your-trunk.pstn.twilio.com)

3. Configure authentication (choose one method):

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Method A: IP Access Control List (Recommended)

1. Click + next to IP Access Control Lists
2. Create a new Access Control List:

• Friendly Name: “Rounded ACL”
• CIDR Network Address: Contact team@callrounded.com for Rounded IPs

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Method B: Credential Lists

1. Click + next to Credential Lists
2. Create new credentials:

• Friendly Name: “Rounded Credentials”
• Username: Choose a username
• Password: Generate a secure password

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Step 4: Associate your numbers

1. Go to Numbers tab in your SIP Trunk

2. If you don’t have numbers yet, click Add a number > Buy a Number
3. Or go to Phone Numbers > Manage > Active numbers
4. Select the number you want to connect
5. In the number configuration:
   • A call comes in: Select “SIP Trunk”
   • Choose your previously created trunk

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Step 5: General Settings (Optional)

• Friendly name: Descriptive name for your trunk
• Call Recording: Enable if needed
• Secure Trunking: Enable for TLS/SRTP
• Call Transfer (SIP REFER): Enable for call transfers

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Step 6: Configuration in Rounded

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Number settings

• Phone number: Your Twilio number (e.g., +15551234567)
• Friendly name: “My Twilio number”

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SIP Trunk settings

• Termination URI: your-trunk.pstn.twilio.com (from step 3)
• Username: Leave empty (optional)
• Password: Leave empty (optional)

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Step 7: Test the configuration

1. In Rounded, create a simple voice agent
2. Assign it to your Twilio number
3. Test:
   • Inbound call: Call your Twilio number
   • Outbound call: Initiate a call from your agent

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Troubleshooting

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”403 Forbidden” error

• Check that the origination URI is correctly configured
• Make sure the trunk is active

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Inbound calls don’t work

• Verify that the number is properly associated with the SIP trunk
• Check the webhook configuration in Twilio

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Degraded audio quality

• Check your internet connection
• Test with UDP protocol if TCP is problematic

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Pricing

• Inbound calls according to your plan
• Outbound calls at Twilio international rates
• Monthly fees for the SIP trunk (consult Twilio pricing)

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Support

• 📧 Rounded Support: team@callrounded.com
• 📖 Twilio Documentation: Twilio SIP Trunking
• 🎫 Twilio Support: Twilio Console > Help & Support