Warm transfer fail
The issue we’re running into is exactly because all the modes in Vapi right now send SIP REFER. Since Twilio/PSTN won’t honor REFER, the transfers never complete.
"id": "a09e2d89-c8ea-4f57-b813-d57b88d9b20f",
"createdAt": "2025-05-29T17:45:14.992Z",
"updatedAt": "2025-10-01T17:56:52.814Z",
"type": "transferCall",
"function": {
"name": "transfer_call_tool"
},
"messages": [
{
"type": "request-start",
"blocking": false
}
],
"orgId": "4d4894ae-9e63-435b-8d2d-d165e6c5d7dd",
"destinations": [
{
"type": "number",
"number": "+15127673628",
"message": "I’m transferring you now to a loan officer at Texas Star Loans {{location}}. ",
"callerId": "+19035517555",
"description": "when the {{location}} is longview",
"transferPlan": {
"mode": "warm-transfer-say-summary",
"sipVerb": "refer",
"summaryPlan": {
"enabled": true,
"messages": [
{
"role": "system",
"content": "Please provide a short summary of the call for the loan officer.\n"
},
{
"role": "user",
"content": "Here is the transcript of the call: {{transcript}}"
}
],
"timeoutSeconds": 10,
"useAssistantLlm": false
}
},
"numberE164CheckEnabled": true
},
{
"type": "number",
"number": "+19036386940",
"message": "I’m transferring you now to a loan officer at Texas Star Loans {{location}}. ",
"callerId": "+19035517555",
"description": "when the {{location}} is mineola",
"transferPlan": {
"mode": "warm-transfer-say-summary",
"sipVerb": "refer",
"summaryPlan": {
We have six phone number all the same sipVerb : refer
I think that’s what vapi gave me as default
"id": "a09e2d89-c8ea-4f57-b813-d57b88d9b20f",
"createdAt": "2025-05-29T17:45:14.992Z",
"updatedAt": "2025-10-01T17:56:52.814Z",
"type": "transferCall",
"function": {
"name": "transfer_call_tool"
},
"messages": [
{
"type": "request-start",
"blocking": false
}
],
"orgId": "4d4894ae-9e63-435b-8d2d-d165e6c5d7dd",
"destinations": [
{
"type": "number",
"number": "+15127673628",
"message": "I’m transferring you now to a loan officer at Texas Star Loans {{location}}. ",
"callerId": "+19035517555",
"description": "when the {{location}} is longview",
"transferPlan": {
"mode": "warm-transfer-say-summary",
"sipVerb": "refer",
"summaryPlan": {
"enabled": true,
"messages": [
{
"role": "system",
"content": "Please provide a short summary of the call for the loan officer.\n"
},
{
"role": "user",
"content": "Here is the transcript of the call: {{transcript}}"
}
],
"timeoutSeconds": 10,
"useAssistantLlm": false
}
},
"numberE164CheckEnabled": true
},
{
"type": "number",
"number": "+19036386940",
"message": "I’m transferring you now to a loan officer at Texas Star Loans {{location}}. ",
"callerId": "+19035517555",
"description": "when the {{location}} is mineola",
"transferPlan": {
"mode": "warm-transfer-say-summary",
"sipVerb": "refer",
"summaryPlan": {
We have six phone number all the same sipVerb : refer
I think that’s what vapi gave me as default
