> 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/help-center/readme/glossary.md).

# Glossary

Acronyms and terms used across the IDlayr documentation. Carrier-industry terms first, then platform-specific terms.

## Carrier and mobile-network terms

**E.164** — The international standard format for phone numbers. Numbers are prefixed with `+` and the country code, e.g. `+447700900000`. All IDlayr API requests expect MSISDNs in E.164 format.

**HLR — Home Location Register** — The carrier-side database that records which subscribers are on which network. IDlayr performs HLR lookups to determine carrier, country, and product coverage for a phone number — exposed in v1 as [Eligibility](https://docs.idlayr.com/products/eligibility).

**MNO — Mobile Network Operator** — The carrier (e.g. AT\&T, Vodafone, T-Mobile). IDlayr integrates directly with MNOs to deliver verifications.

**MO — Mobile-Originated** — An SMS sent **from** the device, as opposed to MT (Mobile-Terminated, sent to the device). Reverse SMS uses an MO flow — the user sends an SMS from their device to an IDlayr-provided number.

**MSISDN — Mobile Station International Subscriber Directory Number** — The standard term for a mobile phone number. Used interchangeably with "phone number" in the docs.

**NV 1.0 / NV 2.1 — Number Verification 1.0 / 2.1** — Two generations of the transport that underpins Secure SNA and Discovery. NV 1.0 requires an active cellular data connection so the carrier can attribute the session. NV 2.1, in active rollout, uses carrier entitlement servers to widen coverage. See [API access models](https://docs.idlayr.com/get-started/concepts/access-models).

**OTP — One-Time Password** — The legacy SMS-based verification pattern that IDlayr's products replace. A server-generated code is sent to the device; the user types it back. Vulnerable to phishing, SIM-swap interception, and friction.

**SIM swap** — In carrier terminology: the user replacing or transferring their SIM card to a new device. In fraud terminology: an attacker convincing a carrier to transfer a victim's number to an attacker-controlled SIM. The IDlayr **SIM Swap** product detects recent SIM changes as a fraud signal.

**SMS — Short Message Service** — The carrier-routed text messaging channel. IDlayr's Reverse SMS product uses it as the trust anchor for verification.

**SNA — Silent Network Authentication** — Verifying a phone number directly with the carrier without an OTP. IDlayr's product based on this is [Secure SNA](https://docs.idlayr.com/products/number-verification/secure-sna).

## IDlayr platform terms

**Allowed Networks** — The set of mobile networks a project is enabled against. Each project explicitly declares which networks it can route verifications to, governed at the platform layer. See [Allowed Networks](https://docs.idlayr.com/get-started/concepts/allowed-networks).

**Callback** — A signed HTTPS POST from IDlayr to a URL you supply, delivered when a check reaches a terminal status. Signed via JWKS — verify the signature before trusting the payload.

**Check** — A verification attempt for a specific phone number, against a specific product. Each check has a `check_id`, a `status` (`ACCEPTED` → `COMPLETED` / `EXPIRED` / `ERROR`), and a result.

**Cloudsmith entitlement token** — A build-time credential that authenticates your build system to IDlayr's private Cloudsmith repositories so it can fetch the SDK binaries. Distinct from the OAuth2 access token used at runtime. See [SDKs](https://docs.idlayr.com/get-started/sdks).

**Credentials** — A project's `client_id` and `client_secret`. Used in the OAuth2 client-credentials flow to mint access tokens. See [Credentials](https://docs.idlayr.com/get-started/concepts/credentials).

**Device API** — A product whose integration includes a device-side step requiring the IDlayr mobile SDK and cellular-pinned routing. Secure SNA and Discovery are device APIs.

**Backend API** — A product called purely from your server, with no IDlayr SDK on the device. SIM Swap, Eligibility, and Reverse SMS are backend APIs. (Reverse SMS has a small device-side step — opening the native SMS composer via an `sms:` URL — but it's not an SDK integration.)

**Eligibility** — Pre-flight check that answers "which IDlayr products are available for a given phone number?" before triggering a verification. See [Eligibility](https://docs.idlayr.com/products/eligibility).

**Enterprise Portal** — The web UI for managing projects, credentials, and verification logs. SSO + RBAC. See the [Enterprise Portal changelog entry](https://docs.idlayr.com/changelog#enterprise-portal).

**Match** — The boolean result of a verification: `true` if the verified MSISDN matches the claimed MSISDN, `false` otherwise. Only present when a check's `status` is `COMPLETED`.

**Project** — The unit of configuration in IDlayr. A project has credentials, allowed networks, a sandbox/production mode, and product scopes. Each customer typically has multiple projects (e.g. one per environment, one per use case).

**Project mode** — `sandbox` or `production`. Sandbox mode lets you simulate verification outcomes via the MSISDN suffix, without real carrier traffic. See [Project modes](https://docs.idlayr.com/get-started/concepts/project-modes).

**Reverse SMS** — IDlayr's [mobile-originated SMS](https://docs.idlayr.com/products/number-verification/reverse-sms) verification product. Backend API.

**RFC 7807** — The IETF standard for HTTP API errors, content-type `application/problem+json`. All IDlayr v1 error responses follow this shape.

**Sandbox** — See *Project mode*.

**Scope (OAuth2)** — The product-specific permission a token carries (e.g. `secure_sna`, `sim_swap`, `eligibility`, `reverse_sms`). Determines which API calls the token authorises.

**Secure SNA** — IDlayr's [Silent Network Authentication](https://docs.idlayr.com/products/number-verification/secure-sna) product. Device API.

**SIM Swap** — IDlayr's [SIM-swap detection](https://docs.idlayr.com/products/risk/sim-swap) product. Backend API. (Not to be confused with the carrier action of the same name — context disambiguates.)

**Workspace** — The top-level container in the IDlayr account model. A workspace holds one or more projects and the team members with access to them. See [Workspaces](https://docs.idlayr.com/get-started/concepts/workspaces).


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