Hello Retell Support Team, I'm experiencing an issue with the transfer_call function in my voice agent. When the agent attempts to transfer a call, I receive the following error: tool_call_id: 5461e08c137d8718 { "status": "Transfer call cannot be completed, probably don't have the permission to perform the transfer. Please inform the customer that the transfer did not go through and offer to try again or assist them directly." } Agent ID: agent_96dbd581643beed6f5cc6dcf63 The transfer_call tool is correctly defined in my agent configuration and is being called appropriately by the LLM, but it seems there's a permission or configuration issue preventing the actual transfer from occurring. Could you please tell me what's this error? Thank you for your assistance.

hi there, is this a sip trunked number?

yes

this could be due to incorrect trunking settings, can you share your destinations?

Could you please explain it more in details? What do you want to see?

your trunking setup, something must be set up wrong

2 calls got this error but then other 5 calls went perfect

can you try changing the outbound transport method to either tcp or udp?

this is the settings that I am using @Colin - Integrations @ Retell AI https://cdn.discordapp.com/attachments/1450235811470770359/1450239733539143680/Screenshot_2025-12-15_alle_22.34.01.png?ex=6941d080&is=69407f00&hm=69d9398dd528c868eec2c934a97fa2a2462e7af2f5b1388799a89e51e0d7b02a&

your termination uri needs to be unique

What can I change here? @Colin - Integrations @ Retell AI

Hello @Matteo , can you share a call id , i checked the last call and it was transferred

2 calls: Call ID: call_421148e6ea6f7541bdd...4d3 tool_call_id: 077ba3cb26f20206 {"status":"Transfer call cannot be completed, probably don't have the permission to perform the transfer.. Please inform the customer that the transfer did not go through and offer to try again or assist them directly."} Call ID: call_7206e71b886ffae30ca...449 tool_call_id: f9b537305732950c {"status":"Transfer call cannot be completed, probably don't have the permission to perform the transfer.. Please inform the customer that the transfer did not go through and offer to try again or assist them directly."}

Hello @Matteo , the calls id looks incomplete

2 calls: Call ID: call_421148e6ea6f7541bdd844384d3 tool_call_id: 077ba3cb26f20206 {"status":"Transfer call cannot be completed, probably don't have the permission to perform the transfer.. Please inform the customer that the transfer did not go through and offer to try again or assist them directly."} Call ID: call_7206e71b886ffae30ca4572d449 tool_call_id: f9b537305732950c {"status":"Transfer call cannot be completed, probably don't have the permission to perform the transfer.. Please inform the customer that the transfer did not go through and offer to try again or assist them directly."}

Hello @Matteo , I checked your call and it have this error :Unverified origination number D51, you can check what it means from here https://support.telnyx.com/en/articles/4409457-telnyx-sip-response-codes

@Omar Ashraf | Community Lead @Colin - Integrations @ Retell AI I had this same issue yesterday morning, between 8am and 12pm Pacific. I got about 13 call transfer that failed because of "Transfer call cannot be completed, probably don't have the permission to perform the transfer..". Other calls transferred successfully in between. Can somebody help me with this intermitant issue?

Hello @Prodestinados , can you create a new ticket and share a call id

Can I ask you how I can solve it? @Omar Ashraf | Community Lead

You can check with the Telnyx team since the error is coming from them.