Voice Call API - Service Specifications, Price Lists, Code Examples, Docu and Applications.

Voice Call API - a simple webservice

Voice Call is a simple web service for connecting any two telephone numbers in the fixed and mobile networks, both nationally and internationally.

It enables, for example, CRM and ERP systems, widgets and apps to be enhanced with telephone functions on a cross-platform basis. Callback buttons, inbound and outbound calls direct from CRM, as well as the automation of processes using voice commands (e.g., for resetting passwords or inputting data) are just as easy to set up as phone calls between members of an online community.


  • No special knowledge of VoIP, PBX, ISDN, etc., required
  • Hardware-independent
  • Standard protocol: REST
  • Extensive documentation
  • SDKs for Java, .NET, PHP, Python & Obj-C
  • Simple to integrate into any software or hardware
  • Robust, scalable infrastructure offered by Deutsche Telekom AG: 24/7 availability
  • Cost control thanks to prepaid mechanism (automatic top-ups possible)
  • Per-minute billing: no provisioning fee, no contract ties and no basic charge
  • No chargeable support agreements
  • Sequential calling to two additional phone numbers possible
  • Any phone number can be dialed: fixed network, mobile, national and international
  • Maximum call duration can be specified in advance

Supported Webservice-Protocols

  • REST (over HTTPS)

Supported programming languages by SDKs

  • Java and all other JVM languages
  • PHP (incl. Typo3 and Zend Framework)
  • C#, Visual Basic and all the other languages on the .NET platform
  • Python
  • Objective-C

Our Voice Call API offers more

The newCallSequenced feature automatically calls a maximum of two additional alternative phone numbers. If the person being called is not directly available under the first phone number, this convenient service offers the possibility of getting through on a different number.

The call duration can be specified beforehand, making it easy to keep complete control of all call costs.

Following registration and activation of the service, Voice Call is available to test free of charge in the sandbox. This mock environment simulates the behavior of services for testing with applications and helps with the software and hardware integration of Voice Call.

Comparison with other solutions

Unlike conventional solutions, Voice Call requires no proprietary protocol, no lengthy familiarization periods and no own PBX server.


Software Development Kits

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