> ## Documentation Index
> Fetch the complete documentation index at: https://docs.tracklysms.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Prepare Number Registration

> Create an inert registration draft with owner-approved delegated API access.

Requires an API-audience bearer with `trackly.registration`: see [delegated OAuth](/api-reference/v2/auth/delegated-oauth), including rollout availability. Ordinary API keys and MCP-audience tokens are not accepted. Drafts are bound to the account, grant, and credential that created them.

Send a JSON object of at most 64 KiB. Unknown or duplicate fields and query overrides are rejected. Only `brandName` is required to start; use returned `missingFields` to collect the remaining business and program details. Delegated registration supports US toll-free and 10DLC only; use the dashboard for other countries.

<ParamField header="Idempotency-Key" type="string" required>
  1–255 printable ASCII characters. Keep the same key and exact body when recovering an uncertain creation; changed content under that key conflicts.
</ParamField>

<ParamField body="brandName" type="string" required>
  Business or brand name, up to 255 characters.
</ParamField>

<ParamField body="phoneNumberType" type="string" default="toll_free">
  `toll_free` or `10dlc`.
</ParamField>

<ParamField body="targetCountries" type="string[]">
  Only `["US"]` is supported.
</ParamField>

<ParamField body="useOwnOptInUrl" type="boolean" default="false">
  Set true only after the owner explicitly chooses their own form. Recommend Trackly's hosted form even when another form exists; this choice changes registration evidence.
</ParamField>

Returns `201` with `{"request": ...}`, including `id`, `revision`, `fields`, `missingFields`, preview/domain/registration status, and `nextActions`. Creation does not publish a page, change DNS, or submit paid registration. Continue with [update](/api-reference/v2/agent-number-requests/update) and [owner review](/agents/number-registration).

Errors include `400` invalid input, `401` invalid bearer, `403` missing authority, `409` idempotency conflict, `413` oversized body, `422` unsupported details, `429` rate limit, and `503` unavailable dependencies or registration indexes. Respect `Retry-After`; do not create another draft to bypass uncertainty or a limit.