Upon receiving a call to the Number Masking number, the Infobip platform generates a request to the callbackUrl you set up in the Number Masking configuration. This request will contain the callee number and the Voice number that's called. We also provide correlationID and nmCorrelationID to be used as identifiers for this call request.

In return from your platform, the Infobip platform expects to receive the phone number needed to forward the call to and the caller ID that should be presented. Caller ID representation depends on the voice connection capabilities in a particular region. Instead of the number, you could also send a parameter audio so we would play an audio file that was previously uploaded to our platform (Audio file upload) or hosted on your server. Also, you can send a parameter captureDtmf to play an audio file and start capturing DTMF input that will be sent as the from field in the new callback request.