receptionist_candidate_agent_routed_elsewhere
The agent already answers another number, directly or through an answering policy. A candidate version would change what that line answers with, so route it away first.
Problem shape
Every non-2xx response is an RFC 9457 application/problem+json body. The type URI below is stable and machine-matchable, so branch on the final path segment (the code) and treat the status as redundant confirmation. See the error-handling guide.
{
"type": "https://docs.vocapable.com/errors/receptionist_candidate_agent_routed_elsewhere",
"title": "…",
"status": 409,
"detail": "…",
"instance": "/v1/…"
}