verified_number_exists
The number already has a live (pending or verified) registration for this tenant. Re-registration restarts only an expired one; a revoked number registers as a fresh row.
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/verified_number_exists",
"title": "…",
"status": 409,
"detail": "…",
"instance": "/v1/…"
}