POST /api/v2/conversations/calls 400: Malformed participant address structure despite valid JSON

Anyone free to help troubleshoot this persistent 400 Bad Request error when attempting to initiate outbound calls via the Platform API for our real-time supervisor dashboard. The endpoint is POST /api/v2/conversations/calls, and while the request body appears structurally sound according to the Swagger definition, the service rejects it immediately. The error payload returned is "message": "Invalid request body" with an inner error code of invalid_request_body. I have validated the JSON against multiple online linters and even the official Genesys Cloud API documentation examples, yet the issue persists. The documentation explicitly states, “The participant address must be a valid telephone number or URI scheme supported by the platform,” which I am adhering to strictly. My current implementation uses a standard application/json header and includes the required from and to addresses in the participants array. However, the specific format of the to address seems to be the point of failure, as removing it allows the request to pass validation checks but obviously fails to route the call. I am operating in the Asia/Tokyo timezone, and while latency is not the issue here, I want to ensure there are no region-specific restrictions on address formatting that are not clearly documented in the standard REST API reference guides.

Here is the exact JSON payload I am sending in the request body. The from address is a verified telephone number in our account, and the to address is a standard E.164 formatted number. I have also tried using the tel: URI scheme prefix, as suggested in some community forums, but the result remains identical. The wrapupCode and routing fields are omitted to simplify the initial test, focusing solely on the connection establishment. The error occurs before any WebSocket events are triggered in the notification service, indicating this is a strict validation failure at the REST API gateway level rather than a downstream routing issue. I have double-checked the OAuth token scope, ensuring it includes conversation:write and user:read, which are the minimum required permissions for this operation. The token is valid and active, as confirmed by a successful GET request to /api/v2/users/me immediately prior to the POST attempt. This eliminates authentication as a potential cause for the rejection. The consistency of the 400 error across multiple test iterations suggests a fundamental misunderstanding of the address schema or a hidden requirement not covered in the public documentation.

The documentation states, “Participant addresses must be properly formatted according to the communication type,” but it lacks specific examples for edge cases involving international dialing codes or special characters. I have tried escaping the plus sign, using raw numbers, and even testing with a local number, but the 400 error persists with the same generic message. Is there a specific regex pattern or validation rule applied to the address field that is not publicly disclosed? I am looking for a concrete example of a working JSON payload for the /api/v2/conversations/calls endpoint that successfully initiates a call with an external participant. Any insights into the internal validation logic or known issues with address parsing in the current API version would be greatly appreciated. I am prepared to provide additional logs or debug traces if necessary, but I suspect this is a common pitfall for developers integrating with the notification and conversation APIs for the first time. The verbose nature of the error response does not help in pinpointing the exact field causing the failure, leaving me to guess at the root cause.

the documentation actually says you need to wrap the participant in an array. try this:

{
 "to": ["+15550001234"],
 "from": ["+15550009999"],
 "participants": [
 {
 "toAddress": "+15550001234",
 "fromAddress": "+15550009999"
 }
 ]
}

i hit this same 400 in my local mock server when i forgot the brackets.

The easiest fix here is this is to ensure the addresses are fully qualified URIs, not just raw numbers. The docs state “participant addresses must include the scheme” so verify your string format.

{
 "participants": [
 {
 "toAddress": "tel:+15550001234",
 "fromAddress": "tel:+15550009999"
 }
 ]
}

If you omit the tel: prefix, the parser rejects it as malformed regardless of the JSON structure.

My usual workaround is to forcing the tel: prefix and ensuring the array structure is strict, as the parser is unforgiving. Never skip the scheme validation step.

{
 "participants": [
 {
 "toAddress": "tel:+15550001234",
 "fromAddress": "tel:+15550009999"
 }
 ]
}

My usual workaround is to validating the token scope rather than just the payload structure. The suggestions above regarding the tel: scheme are correct, but if you still receive a 400, check your OAuth scopes.

I debugged a similar issue last week where the token had conversations:read but lacked conversations:write. The API rejects the body before parsing if the scope is insufficient. Ensure your client credentials request includes conversations:write in the scope list.

Here is the curl command to verify your token scopes:

curl -X GET "https://api.mypurecloud.com/api/v2/oauth/me" \
 -H "Authorization: Bearer <YOUR_ACCESS_TOKEN>"

If conversations:write is missing, rotate your secret and re-authenticate. I use HashiCorp Vault to manage this rotation, ensuring the new token has the correct least-privilege scopes. Do not use a service account with full admin rights just to fix this. It creates a security risk. Check the scope first.