The Voice API Apps are a set of pre-configured apps for outbound scenarios. Currently, the set consists of the following three apps:

Notification (Billing per minute)

One Time Password (OTP) (Billing per OTP message)

Request DTMF (Billing per minute)

These apps can be initiated by sending a request to the CM Server(s), which will initiate the call and once answered, will complete the process (flow) of the app.


Sending a Notification means sending a call that simply plays some audio and then hangs up. This audio can be spoken text (either using a custom audio file or our Text-To-Speech system), a commercial or any audio you can think of.

One Time Password (OTP)

Sending a One Time Password uses a bit more elaborate approach. This call contains a welcome message, the code (password), an outro, etc. It also allows the end user to press '1' to have the code repeated.

Every single piece of audio in an OTP call can be a custom audio file or a piece of text that is read by our Text-To-Speech system.

Request DTMF

DTMF, or Dual Tone Multi-Frequency, is the technique of using the numeric keys on your phone for input. Using this technique, we can send a call to end users, asking them to enter a code. This can for instance be used for authentication, to opt-in to a service or to accept an emergency call.