POST /api/v2/conversations/calls 400 Bad Request: Malformed Participant Address in Node.js Middleware

NICE CXone API & Integrations
1

I’ve spent hours trying to figure out why my Node.js middleware service keeps receiving a 400 Bad Request when attempting to initiate outbound calls via the CXone API.

The error response is explicit:

{
 "errors": [
 {
 "code": "malformed",
 "message": "The participant address is malformed.",
 "parameter": "to"
 }
 ]
}

I am using the axios library to make the request. The endpoint is POST https://{{domain}}.mygenesys.com/api/v2/conversations/calls. I have verified that my OAuth token has the conversation:write scope. The issue seems to be strictly with the payload structure.

Here is the request configuration I am using:

headers:
 Content-Type: application/json
 Authorization: Bearer {{access_token}}
 X-Genesys-Deployment-Id: {{deployment_id}}

payload:
 to:
 phoneNumber: "+1-555-019-2834"
 from:
 phoneNumber: "+1-800-555-0100"
 routingType: "longestIdle"
 wrapUpCode: "default"

I have tried multiple variations of the phone number format. Removing the country code prefix (+1) results in the same error. Using E.164 format without dashes (e.g., +15550192834) also fails. I even tried passing the number as a string directly instead of an object, but the schema validation rejects that immediately.

Given my experience with the Event Hub and real-time agent state APIs, I am used to strict JSON schemas, but this one feels particularly unforgiving regarding the to field. Is there a specific regex pattern the CXone API expects for the phoneNumber field in this specific endpoint? Or is there a hidden requirement for the from address that I am missing?

I am running this from an AWS Lambda function in the Asia/Kolkata region, so latency is not the issue here. Any insights into the exact string formatting required would be appreciated.

2

The to field requires a fully qualified tel: URI, not just digits. The Node.js SDK handles this, but raw axios requests need explicit formatting. Use tel:+1234567890 instead of 1234567890.

  • Verify OAuth scope includes conversation:call:write
  • Check E.164 number formatting strictly
  • Inspect request body JSON structure for missing from
3

You need to validate the URI scheme before the request hits the wire.

In my Playwright E2E suite, I wrap the outbound call logic in a page object that asserts the to field matches ^tel:\+?[0-9]+$ before invoking the API. If your middleware is stripping the tel: prefix or injecting whitespace, the Genesys Cloud API will reject it with that exact malformed error. Use this regex validation in your Node.js middleware to catch it early:

const isValidTelUri = (phone: string) => /^tel:\+?[0-9]+$/.test(phone);
4

Make sure you are strictly enforcing the E.164 format with the tel: scheme in your axios payload, as the API parser is notoriously strict about URI compliance. The suggestion above regarding regex validation is correct, but I often see this fail because of hidden whitespace or missing country codes in the middleware layer. Since I deal with identity provisioning, I know how sensitive API gateways are to malformed strings, and Genesys Cloud is no different. You should normalize the input before sending it. Here is a quick Node.js snippet to sanitize the number:

const normalizeTel = (num) => `tel:+${num.replace(/\D/g, '')}`;
const payload = { to: normalizeTel('1234567890'), from: 'tel:+1987654321' };

Also, double-check that your OAuth token has the conversation:call:write scope. A 400 error can sometimes mask a scope mismatch if the request body is slightly off, but usually, it is just the tel: prefix missing. Ensure your JSON structure matches the API spec exactly.

5

I think the parser rejects the payload if the tel: scheme isn’t strictly lowercase or if there’s trailing whitespace in the JSON string, so sanitize the input before serialization.

  • validate tel: scheme casing
  • trim whitespace from phone numbers
  • verify conversation:call:write scope