How to connect Retell AI voice agents with Wavix

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Prerequisites

1. An active phone number in your Wavix account. If you need to purchase one, see our guide on how to buy a phone number.
2. A Wavix SIP trunk (How to create a SIP trunk).
3. An active Retell AI account.

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How it works

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Inbound calls

1. A customer calls your Wavix phone number.
2. Wavix routes the call via SIP to your Retell AI voice agent.
3. Retell AI voice agent processes the audio and generates responses.
4. Responses are streamed back into the call through Wavix.

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Outbound calls

1. Your application or Retell AI dashboard triggers a call.
2. Retell AI connects to Wavix via SIP.
3. Wavix connects the call to your customer via the telephony network.
4. The customer answers the call.
5. Retell AI voice agent processes the audio and generates responses.
6. Responses are streamed back into the call.

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Receive calls with Wavix and Retell AI

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Import a number into Retell AI

• Retell AI dashboard
• API

1. Sign in to your Retell AI account.
2. In the left-hand menu, select Phone Numbers.
3. Select the + button and choose Connect to your number via SIP trunking.

4. Enter the imported Wavix number details:
   • Phone Number: A Wavix phone number in your account.
   • Termination URI: Use us.wavix.net to ensure the lowest audio latency.
   • SIP Trunk User Name: Enter the SIP trunk ID from your Wavix account.
   • SIP Trunk Password: Your Wavix SIP trunk password.
   • Outbound Transport: Use TCP.
5. Select Save.

Import a number with the Retell AI Import phone number endpoint. Run the POST request below using your favorite tool, such as Postman or terminal.

curl -X POST "https://api.retellai.com/import-phone-number" \
  -H "Authorization: Bearer YOUR_RETELLAI_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "phone_number": "+YOUR_WAVIX_NUMBER",
    "termination_uri": "us.wavix.net",
    "sip_trunk_auth_username": "YOUR_SIP_TRUNK_ID",
    "sip_trunk_auth_password": "YOUR_SIP_TRUNK_PASSWORD",
    "transport": "TCP",
    "nickname": "Wavix number"
  }'

• Replace YOUR_WAVIX_NUMBER with a number on your Wavix account in E.164 format with the leading + sign, i.e., +61290597521.
• Replace YOUR_SIP_TRUNK_ID and YOUR_SIP_TRUNK_PASSWORD with the SIP trunk credentials configured in the Wavix portal.
• Replace YOUR_RETELLAI_KEY with your Retell AI API key.

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Create a Retell AI voice agent

1. In your Retell AI dashboard, open the left-hand menu and select Agents.
2. In the top-right corner, select Create an Agent and choose Voice Agent.
3. Select an Agent Type and use one of Retell AI’s templates or build a new agent from scratch.
4. Once finished, publish your agent:
   • Give your agent a descriptive name.
   • (Optionally) Provide information about what your agent does.
   • Associate it with an imported phone number.

5. Select Publish.

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Configure your Wavix number

1. In the Wavix portal, open Numbers & trunks → My numbers.
2. Select your number by clicking the ⋯ menu → Edit number.
3. Set the inbound call destination type to SIP URI, and enter the destination:

[did]@sip.retellai.com;transport=tcp

4. Select Save to apply changes. Wavix will automatically replace [did] with your actual number.

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Verify the configuration

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Place calls with Wavix and Retell AI

• An Outbound Call Agent is assigned to the number.
• The country you plan to call is listed in Allowed Outbound Countries or all countries are allowed.

• Dashboard
• API
• Batch Call tool

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Place a call using the dashboard

1. In the left-hand menu, select Phone Numbers.
2. Choose the imported Wavix number.
3. In the top-right corner, select Make an outbound call:
   • Phone Number: Enter the number you want to call.
   • Dynamic Variables: Provide dynamic variables to prepopulate in your assistant.

4. Select Call.

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Place a call using API

1. Navigate to Settings and select API Keys.
2. Copy your API key.

3. Run the POST request below using your favorite tool, such as Postman or terminal.

curl -L 'https://api.retellai.com/v2/create-phone-call' \
-H 'Authorization: Bearer YOUR_RETELLAI_KEY' \
-H 'Content-Type: application/json' \
-d '{
    "from_number": "+YOUR_WAVIX_NUMBER",
    "to_number": "+DESTINATION_NUMBER",
    "ignore_e164_validation": false
}'

• from_number: Originating number, the Wavix number imported to Retell AI.
• to_number: Destination number you want to call.

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Batch Call tool

1. In the Retell AI dashboard, navigate to Batch call and select Create a batch call.
2. Give your campaign a name and select an imported Wavix number.
3. Upload a list of contacts.
4. (Optionally) Schedule your campaign.
5. Select Send to launch the campaign.

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Send a call follow-up SMS

• Register the SMS Sender ID you want to use. For setup instructions, see Sender ID registration.
• Create a dedicated Wavix API key with only the scopes required to send SMS.
• Confirm that the caller has agreed to receive the follow-up SMS.
• Keep the SMS content short and include opt-out text when required by your destination country or messaging use case.

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Connect the Wavix MCP server to Retell AI

curl -X GET "https://api.retellai.com/get-mcp-tools/YOUR_AGENT_ID?mcp_id=YOUR_WAVIX_MCP_ID" \
  -H "Authorization: Bearer YOUR_RETELLAI_KEY"

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Capture the caller number

• For inbound calls, the caller number is from_number.
• For outbound calls, the customer number is to_number.

• For inbound calls, set follow_up_number to the inbound from_number.
• For outbound calls, set follow_up_number to the outbound to_number.

If the caller asks for a written follow-up and confirms consent, use the Wavix SMS tool to send one message to {{follow_up_number}} from SENDER_ID. Keep the message under 160 characters when possible. Do not send sensitive personal, payment, authentication, or health information by SMS.

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Security requirements

• Use a Wavix API key scoped only to messaging. Don’t use a full-access account key.
• Store API keys only in Retell AI MCP server headers or another protected secret store. Don’t put keys in prompts, dynamic variables, or public URLs.
• Require caller consent before sending an SMS. The agent should not send follow-ups automatically for every call.
• Use API key scopes to limit the Wavix MCP tools available to the agent.
• Don’t send one-time passwords, payment details, health information, or other sensitive data in a follow-up SMS.
• Follow destination-country SMS rules, including Sender ID registration, opt-out language, and message content restrictions.
• Review Retell AI data storage settings if you redact Caller IDs or dynamic variables. If phone_number is redacted, Retell AI removes the customer number from the call record.
• Monitor Wavix message delivery reports and Retell AI function or MCP node logs during rollout.

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Call transfer

1. In your Retell AI dashboard, select the agent you want to enable this functionality for.
2. Under Functions, click Add and choose Call Transfer.
3. Set the Transfer to to Static Destination and enter a SIP URI to transfer the call to in the following format: sip:[YOUR_WAVIX_NUMBER]@us.wavix.net. Example: sip:14062260605@us.wavix.net.
4. Make sure to select Keep raw input.
5. Select Cold Transfer under How should the AI handle the transfer?.
6. Select SIP REFER as the SIP Transfer Method.
7. Select Save.

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Troubleshooting

1. Validate that the destination number is in E.164 format (e.g., +14155552671).
2. Confirm the destination country is listed under Allowed Outbound Countries in Retell AI’s phone number settings.
3. Verify your Wavix account has sufficient balance for the outbound call.
4. Check that your Wavix CPS (calls per second) limit is not exceeded. By default, Wavix allows 3 CPS. Contact support@wavix.com to increase this limit.

1. In the Wavix portal, verify that the inbound call destination for your number is correctly set to [did]@sip.retellai.com;transport=tcp.
2. Confirm that an Inbound Call Agent is assigned to the number in Retell AI’s phone number settings.
3. Check that your Retell AI agent is in Published status, not in draft mode.

1. In the Wavix portal, navigate to Numbers & trunks → Trunks and verify the SIP trunk credentials.
2. Confirm the SIP trunk ID and password match exactly what you entered in Retell AI’s phone number configuration. Credentials are case-sensitive.

1. In your Retell AI dashboard, verify the agent is assigned to the imported phone number.
2. Check that your agent’s LLM (language model) is properly configured and has the correct prompt.
3. Test your agent directly from the Retell AI dashboard to ensure it responds correctly.
4. Review Retell AI logs for any errors related to the agent’s LLM or TTS service.

1. Verify the SIP Trunk User Name is your actual SIP trunk ID (not your Wavix account ID).
2. Double-check the SIP Trunk Password has no extra spaces or special characters that might have been mistyped.