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not_implemented

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This endpoint or channel is not live yet during the beta.

HTTP 501. This endpoint or channel is not live yet during the beta.

What it means

Section titled “What it means”

Flow Messaging is in beta. Some endpoints and channels are in the spec before they are live, and answer not_implemented until then.

Why it happens

Section titled “Why it happens”
  • Asking for an iMessage line, a WhatsApp number or a US SMS number with POST /v0/senders: these are connected by the Flow team, not by API. This answer comes first, with a test or a live key.
  • An endpoint that arrives in a later release.

How to fix it

Section titled “How to fix it”

Build on what is live now (Telegram, iMessage replies, and the endpoints that answer). For an iMessage line, a WhatsApp number or a US SMS number, write to the Flow team at samyak@flow.engineer or prabal@flow.engineer with your app ID (GET /v0/app) and the number’s details, never secrets or tokens; it then appears in GET /v0/senders with your live key. Meanwhile, build and test on simulated conversations of that channel with a test key (POST /v0/test/conversations with "channel": "imessage", "sms" or "whatsapp"): they keep the channel’s rules and need no number.

curl https://api.flow.engineer/v0/senders -H "Authorization: Bearer $FLOW_MESSAGING_KEY"   # what you can send from today

Every error also carries hint, one sentence specific to your request, and doc_url, this page. Coding agents connected to Flow’s MCP server (https://api.flow.engineer/mcp) can call explain_error with the type to read this page.