We encountered an issue where a human picked up the call but never heard the agent. What is weird in the call recording, we can hear both the Human and AI. Our setup is Twilio with a SIP Phone on the VAPI side. Could the problem be on the VAPI side? Example CALL ID: 0199f20a-e150-7115-9eff-bf0c61cca11b

Suggestion: To diagnose whether the issue is on the Vapi or SIP side, download the SIP packet capture (PCAP) for the affected call and analyze it in Wireshark. Run:

curl -X GET "https://api.vapi.ai/call/0199f20a-e150-7115-9eff-bf0c61cca11b" -H "Authorization: Bearer YOUR_API_KEY"

Look for audio stream issues, missing REFER packets, or codec mismatches. This will help pinpoint if audio is being sent correctly from Vapi to your SIP endpoint. Reference: [Vapi SIP troubleshooting guide](https://docs.vapi.ai/phone-calling/transfer-calls/debug-forwarding-drops) Source: - [Debug call forwarding drops](https://docs.vapi.ai/phone-calling/transfer-calls/debug-forwarding-drops)

Hi @Dmytro. We have been experiencing this same problem here.

Hi Dmytro, For setting up silent transfers to ensure a seamless call experience, follow these steps: 1. **Destination Assistant's First Message**: - Set the

firstMessage

to an empty string. - Set

firstMessageMode

to

assistant-speaks-first-with-model-generated-message

. 2. **Squad's Assistant Destinations Messages**: - For every

members[*].assistantDestinations[*]

, set the

message

property to an empty string. 3. **Source Assistant's Prompt**: - Include a line instructing it to transfer to the desired assistant:

json
     trigger the transferCall tool with 'assistantName' Assistant.

- Replace

'assistantName'

with the exact name of the next assistant. 4. **Destination Assistant’s Behavior**: - Include a line in the prompt:

Proceed directly to the Task section without any greetings or small talk.

For further details, you can refer to the [documentation](https://docs.vapi.ai/squads/silent-transfers).

This is not even related to the conversation

For SIP-based calls where audio is present in recordings but not heard by participants, here's how to investigate: 1. First, check the call logs to verify Vapi successfully initiated the call: - Get the call details using the call ID - Look for the

endedReason

to see how the call terminated - Check if there are any SIP-related errors 2. Since you're using SIP phones with Twilio, you should: - Analyze the SIP packets using Wireshark (you can get the PCAP file from Vapi's API) - Look specifically for proper media negotiation in the SIP signaling - Check if there were any RTP stream issues 3. Common causes for this issue could be: - SIP endpoint configuration mismatches - Media routing issues between Twilio and Vapi - Call control settings conflicts To resolve: 1. Verify your SIP configuration 2. Ensure

phoneCallProviderBypassEnabled

is set to

false

3. Check for any conflicting call control settings If the issue persists after these checks, you should: 1. Gather the call ID, timestamp, and PCAP analysis 2. Include screenshots of your configuration settings

I would like kindly to ask if you can allow me to become an enterprise partner

Thank you for your interest in Vapi’s enterprise plans. To help us expedite this process and connect you with the right team, could you please provide the following details: - Company size (number of employees) - Company location Once we have this information, we’ll be able to guide you toward the best plan and support options for your needs.

Thank you, Kyle, for your reply. We currently have 7 team members — 5 developers, 1 sales representative, and myself (the founder), who also works as a developer. We are based in Brazil. Looking forward to hearing back from the VAPI team.

Thanks for getting back to us and updating us We’ll share an update as soon as more information becomes available. We appreciate your understanding and patience as we continue our investigation.