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How to call PSTN

Voximplant supports calls from any endpoint to the cloud and from the cloud to any endpoint including PSTN numbers. Thus, a traditional phone-to-phone call is split into two "call legs": from the first phone (or SDK) to the Voximplant cloud and from the Voximplant cloud to the second phone (or SDK), with the audio streams from both calls connected via a cloud-based JavaScript code.


While technically no source phone is involved in calling a target phone number from the cloud, some phone number should be displayed to the callee so that they can call back. You can specify a number rented from Voximplant or any number you own if you confirm it in the Voximplant control panel.

Restricted directions

Calls more expensive than 20 cents per minute and calls to Africa are blocked by default for security reasons. To enable them, contact us at support@voximplant.com. The callPSTN method triggers the CallEvents.Failed event in 60 sec, see the details in VoxEngine session limits.

Calling PSTN

Use the callPSTN method in your scenario to call a specified number. So, when you run it, a call will land on the phone number specified in the JavaScript code.


Here is what we set for the method:

  • number (PSTN) to start a call (in international format (E.164))

  • callerid of the calling user that will be displayed to the callee. Whitespaces are not allowed. A valid phone number that can be used to call back is required. The following phone numbers can be used:

  1. A real phone number that is rented from Voximplant. IMPORTANT: test numbers can't be used
  2. Any phone number that is verified via an automated call from Voximplant and confirmation code
  3. A phone number from an incoming call to the rented number. It can be retrieved as Caller ID
Usage sample

Usage sample

Put this code to your Voximplant scenario