Use Case

A voicemail using a single communication engine

As all communication engines exposes APIs so they can be programmed to perform specific service logic, this use case demonstrates how the CPAAS-AEF can be used to build a voicemail application without having the need to rely on any other communication engine. CPAAS-AEF exposes enterprise Unified Communication APIs to embed Voice, Messaging and Presence services into business applications. It relies on SIP/RTP and SMPP communication protocols.

The CPAAS-AEF expose several families of APIs, for this use case, we are going to use:

  • The SIP call control API for call setup and teardown
  • The Multimedia API for voice playback, recording and DTMF detection
  • The SMPP API for text notifications
Single Cloud Communication Engine Use Case: a Voicemail application connects to CPAAS-AEF via SIP API, VOICE API and SMPP API; CPAAS-AEF connects to an SMPP Provider and to an IP-PBX or Public switch via SIP/RTP.

As decribed in the diagram above, the voicemail application interacts with the CPAAS-AEF which abstracts the SIP and SMPP telecom interfaces towards the private or public telephone switch.

The voicemail service is composed from 2 main call flows, one for leaving a message to a subscriber currently not available to take a call, and the other for the subscriber to retrieve the messages left for him. This article does not refers to the way the message themselves are stored and it which format they are stored. Our aim here is to illustrate how a single communication engine can stand for itself without necessarily being a part of a workload.

Call Flow for leaving a message

Call flow for leaving a voicemail message: the Voicemail application and the IP-PBX or Public switch exchange SIP INVITE, TRYING, 200 OK and ACK via the CPAAS-AEF; the application then uses the CPAAS-AEF call control and multimedia APIs to detect the connected call, play a prompt, record the message, drop the call and send an SMPP text notification.

Call Flow for retreiving a message

Call flow for retrieving voicemail messages: the Voicemail application and the IP-PBX or Public switch exchange SIP INVITE, TRYING, 200 OK and ACK via the CPAAS-AEF; the application then uses the CPAAS-AEF call control and multimedia APIs to detect the connected call, play back each stored message with DTMF digit collection between messages, announce the end of the mailbox and drop the call.

What other engines can be used in a single or standalone mode?

Any API Exposure Functions can be used in a standalone mode and help you to develop an application in your preferred programming language using its swagger file (openAPI document). Full list of API Exposure Functions and their respective documentation can be found here.

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