POST /api/v2/conversations/calls returns 403 Forbidden for agent-initiated outbound

NICE CXone API & Integrations
1

We’re building a sidecar to initiate outbound calls on behalf of agents for New Relic tracking. Using the REST API POST /api/v2/conversations/calls. The service has the conversation:write scope, but the request fails with HTTP 403 Forbidden. The agent ID exists and is online. Here is the payload:

{
 "to": {"phoneNumber": "+15550199"},
 "from": {"phoneNumber": "+15550100"},
 "agent": {"id": "12345"}
}

Any ideas on the specific role requirement missing?