AT&T

AT&T In-App Messaging API

A messaging API enabling applications to send, receive, update, and delete MMS and SMS messages on behalf of users with explicit consent. Supports messages to phone numbers, short codes, and email addresses across AT&T and other carriers, with inbox management and delta synchronization.

GitHub OpenAPI

Documentation

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Documentation
https://developer.att.com/in-app-messaging/docs
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Authentication
https://developer.att.com/oauth-2/docs

Specifications

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OpenAPI
https://raw.githubusercontent.com/api-evangelist/at-and-t/refs/heads/main/openapi/at-and-t-in-app-messaging-api.yaml