Introduction
API Description
The Calls API can be used to call fixed and mobile telephone numbers and invoke predefined static or dynamic scenarios for this interaction.
The endpoint for this interaction is always the Developer Platform API server. To establish a call between two (or more) parties, the API server will call each party individually and bridge the call legs.
The enabled call scenarios fit in the category of Application-to-Person (A2P) scenarios. Despite this classification being often used for messaging, the calling scenarios are similar: An application queries the API and establishes one or multiple calls to interact with any telephone in the world.
The back channel is not provided, i.e., numbers cannot be called back to interact yet. If certain use cases require this, the preconditions need to be arranged on an individual base.
Constraints
The usage of the API is only permitted if calling party phone numbers are used that belong to the sender or for which the sender has a right of use. In the future, mechanisms will enforce this, but they have not been implemented yet. Any misuse violates the agreement under which the API is made available and access will need to be revoked.
The API has global reach, but some countries or operators may have been disabled. If you encounter unforeseen issues please get in touch.
Component Overview
An overview of all components is shown in the following figure:
Benefits
Best carrier network
The API uses Telekom Global Carrier's intercarrier voice platform. High-quality routes between all Deutsche Telekom Group companies and almost every other carrier in the world.
Plug & Play
Easily integrate our Calls API: A single request grants access to Telekom's infrastructure and best connectivity between carriers.
Programmable API
The Telekom Telephony service many customers already rely upon. Now with a modern programmable RESTful API.
Use Cases
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Click-to-Call
IndustryBy adding our Calls API to your online shop, customers will be able to initiate a voice call with a customer service agent with just a single click

Travel Alerts & Notifications
IndustryUse our SMS API to provide travelers with up-to-the-minute information about their journey status

Customer Alerts
Ease of UseBy adding push notifications to your app, you can communicate with users in real-time, updating them on the location and timing of upcoming deliveries