> For the complete documentation index, see [llms.txt](https://docs.idlayr.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.idlayr.com/api-reference/eligibility/introduction.md).

# Introduction

The IDlayr Eligibility API answers a single question: **which IDlayr products is this user eligible to use?** Use it before starting a verification flow to decide whether to proceed or fall back to an alternative path.

A user is eligible for a given IDlayr product only when all three of these hold:

* **Connectivity** — IDlayr has connectivity to the user's MNO.
* **Authorisation** — your project is approved to use that MNO and has the corresponding allowed network in place.
* **Product support** — the user's MNO (or MVNO) is supported for the IDlayr product in question (Secure SNA, SIM Swap, Reverse SMS, Discovery).

Eligibility is therefore both a technical check (is there connectivity?) and a commercial check (is your project authorised?). When any of the three conditions fails for a product, that product is not returned in the response.

Two lookups are available:

* **By mobile IP address** — resolve the mobile network behind a device IP (IPv4 or IPv6) and the products the user is eligible for on that network.
* **By phone number** — resolve the mobile network a phone number belongs to (via HLR) and the products the user is eligible for.

Both are synchronous reads. Requests authenticate with an OAuth2 Access Token in the `Authorization` header (`Bearer {access_token}`). Tokens are created using a project's `client_id` and `client_secret`.


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