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Voice Callout API

Voice Call-out API Overview

Our Voice Call-out API allows you to make a call between 2 phone numbers. The first number is one of your Proximus numbers which will be used as the origin of the call and the second number is the destination number.

The main benefits of the Voice Call-Out solution are in its simplicity and the fact that you can reuse your Proximus numbers and pre-existing tariff plans. If you have a fixed voice product with Proximus, all you have to do is subscribe to the service on Proximus EnCo at no extra costs. Any of the voice traffic generated through the API will be using your current voice infrastructure as if it were just a normal voice call.

This service is ideal if you're thinking about your digital transformation and how to automate some of your business processes. Because the solution is so simple you can easily implement proof of concepts around voice call automation.

Use cases

  • CRM integration: You can automate voice calling from you CRM system. For example, when a specific action is taken for a customer such as closing a case or when a phone appointment is scheduled, your CRM system can automatically generate a call between your customer and his account manager.

  • Call reminders / call me back: Off-load some of your inbound calling flows by letting your customers request a "call back". These callbacks can then be picked up from the callback queue by agents that are available.

  • Calendar and contact integration: Let your calendar application generate calls at the right time with the right person by integrating the voice calls with your contact list and your agenda. You can also make sure that your official company numbers are always displayed and reserve direct mobile numbers for more personal interactions.

Using the Voice Call-out API

Call flow

Let's assume the following: the voice call-out API is used for a call to be generated between an account manager with number A (a Proximus number) and his customer with number B (the destination number).

Example flow for VCA API Call


  • Call automation and integration to third-party applications such as CRM, ERP, ticketing.
  • Masked number
  • Reuse your existing Proximus numbers, voice infrastructure, tariff plans at no extra cost
  • Legal compliance such as lawful intercept
  • API Security: anti-spoofing, Oauth based authentication, Proximus account check

Request details

The API request is a HTTP POST with a JSON body that contains 3 parameters. Origin and destination are mandatory parameters and "presentation" is optional. The response if successful is always a sessionId. The sessionId is reserved for future use but can already help for potential support issues.

  • origin (aka "A number"): That is the number that will be called first. It must be a fixed Proximus number owned by the account making the call request. It should be in the E.164 format (although we autocorrect some known formats, we strongly recommend the use of E.164). Note that if a call forward is enabled on the A number, the service will still work.

  • destination (aka "B number"): That is the number that will be called if the first call to the A number is answered. It can be any number (fixed national, mobile, international…) with some restrictions towards special numbers like emergency services . Like the origin number, the number format should be E.164. Note that the current solution does not support any call barring that would be in place. Should you want to implement any call barring logic, this should be part of your application logic.

  • presentation: That optional parameter determines if the A number should be displayed to the B party. The value of this parameter is defaulted to "ALLOWED" if not present or empty. The other authorized value for "presentation" is "RESTRICTED". If "RESTRICTED" is used, the first call will still show the A number to A, but will mask the A number to B.

Request example:

curl -X POST -H 'Authorization: Bearer <YourToken>' -H 'Content-Type: application/json' -d '{"origin": "+3228160257", "destination": "+32468373901", "presentation": "ALLOWED"}'

Response body example:

{"sessionId": "123456"}

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