# Listrak SMS API

> REST API for managing SMS contacts, phone lists, segmentation, sender codes, and sending broadcast and transactional SMS messages.
> Base URL `https://api.listrak.com/sms`. Auth: OAuth2 client_credentials at `https://auth.listrak.com/OAuth2/Token` (Bearer token).
> Collections are cursor-paginated — page with `cursor` and follow `nextPageCursor` (there is no offset/`startIndex`).
> This documentation is plain markdown, designed to be fetched and read directly by coding agents.

## Start here
- [Getting started](https://api-docs.tools.listrak.com/sms/guides/getting-started.md): authenticate and make your first SMS API request
- [Authentication (OAuth2)](https://api-docs.tools.listrak.com/sms/guides/authentication.md): client_credentials flow, token caching, scopes, 401 handling
- [Pagination (cursor-based)](https://api-docs.tools.listrak.com/sms/guides/pagination.md): page phone lists and contacts with cursor and nextPageCursor
- [Errors & retries](https://api-docs.tools.listrak.com/sms/guides/errors.md): error envelope, retryable vs non-retryable codes
- [PII & logging](https://api-docs.tools.listrak.com/sms/guides/pii-logging.md): never log raw phone numbers; safe identifiers and masking
- [Copy-paste client & recipes](https://api-docs.tools.listrak.com/sms/guides/recipes.md): full Python + TypeScript client, subscribe contact, send transactional SMS

## Core resources
- [Contact](https://api-docs.tools.listrak.com/sms/reference/contact.md): A Contact resource is used to manage SMS Contacts.
- [PhoneList](https://api-docs.tools.listrak.com/sms/reference/phone-list.md): A Phone List resource is used to retrieve SMS List information for Sender Codes.
- [Segmentation](https://api-docs.tools.listrak.com/sms/reference/segmentation.md): A Segmentation resource is used to retrieve profile fields.
- [SenderCode](https://api-docs.tools.listrak.com/sms/reference/sender-code.md): A Sender code resource is used to retrieve Sender Code information for a company.
- [ContactListSubscription](https://api-docs.tools.listrak.com/sms/reference/contact-list-subscription.md): A Contact List Subscription resource is used to retrieve and maintain SMS Subscriptions between SMS Lists.

## Sending
- [BroadcastMessage](https://api-docs.tools.listrak.com/sms/reference/broadcast-message.md): A Message resource is used to send an SMS broadcast message to an SMS List, from a specified Sender Code.
- [TransactionalMessage](https://api-docs.tools.listrak.com/sms/reference/transactional-message.md): A Campaign resource is used to retrieve SMS Transactional Lists and send SMS Transactional Messages.

## Optional
- [Full reference (single file)](https://api-docs.tools.listrak.com/sms/llms-full.txt): everything concatenated
- [OpenAPI spec](https://api-docs.tools.listrak.com/sms/openapi.json): machine-readable Swagger 2.0