Delivering Audio Content to Mobile Audiences

Posted by MelissaUlbricht on Dec 20, 2010

Prabhas Pokharel contributed research and writing to this article.

We turn now from producing video on your mobile to audio to show you different ways that people are delivering content to mobile phones. Sending audio content can help you reach new and increasingly mobile audiences. It can also be a great way to reach semi- or illiterate populations or others for whom written content is not suitable.

There are many channels to deliver audio content to mobiles: calling listeners, providing numbers for them to call, having mobile web or app-accessible radio, or leveraging radios that are included in many mobiles. This post will focus primarily on projects and tools that use phone calls, or the "voice channel," to share content.

There are quite a few projects that disseminate audio content using the voice channel:

  • Freedom Fone was deployed at two farm radio stations in Africa.
  • Gaon ki Awaaz provides listeners in rural India with audio content twice a day in their native language.
  • Avaaj Otalo lets farmers call in and listen to archived radio broadcasts in rural India.
  • Geocell and Radio Greenwave in Georgia make short broadcasts available to listeners if they dial a specified number.
  • Listeners can call in to hear podcasts in the United States.
  • In India, Bubbly allows content providers to upload messages that can be broadcast to a list of followers. Listeners can follow audio content from Bollywood celebrities.

How it's being done

This article will give a basic overview of how voice-based technology is used to deliver audio content to a mobile audience. There are many other ways to share audio via data channels such as podcasts, audioblogging, mobile web radio, and apps. We'll revisit data channels in a later post.

There are many voice channel options available, including standard phone calls, call-in podcasts, IVR systems, self-hosted systems, and voice-based content management systems.

Humans answering phone calls

The simplest voice-based services can be provided by a team of operators who answer phone calls and provide information to callers. There is no need for users to go through complicated menus, or for automated voice processing, which makes such systems easy to use and install. Question Box is one example.

Call-in Podcasts

Podcasts are a very simple way to upload audio and some services let listeners call in to listen to podcasts in select countries. The service Podlinez provides publishers a United States phone number that listeners can call. Bubbly is another example of a call-in podcast.

Simple IVR systems

Interactive Voice Response systems are commonly used to access audio information. Callers are prompted with menus, which they can navigate by pressing numeric buttons on their phone keypad or uttering short audio commands. Simple IVR menus can be built fairly easily:

  • VoiceXML is a specification that is widely used to develop IVR menus. VoiceXML is a simple specification language like HTML or XML. In the same way HTML code is interpreted by a web browser to produce a webpage, a "VoiceXML browser" can interpret VoiceXML code to produce an interactive voice response system.
  • In the U.S., hosted solutions like Bevocal cafe offer ways to get started with VoiceXML.
  • VoxPilot VoxBuilder offers local numbers in many other countries. More providers are available at
  • For diving into VoiceXML development, a great resource is World of VoiceXML.

Self-hosted systems

Another way of delivering voice-based audio content to a mobile audience is a self-hosted telephony system. There are a number of open-source platforms that provide code for many self-hosted telephony systems: Asterisk, Trixbox, and FreeSwitch.

There are many resources available for working with these tools.

  • Asterisk has a dedicated documentation project. There are also sites that offer video tutorials and many books have been written on the topic. There are also third party companies that will provide you with support services.
  • Freeswitch has an extensive wiki for documentation. There are forums outside the main site and third-party support services are also available.
  • Trixbox documentation is listed on the Trixbox wiki. Trixbox has a professional version that comes with support services.

Voice-based Content Management Systems

Finally, there some voice-based content management systems in development, which aim to make voice-based telephonic as easy to install as standard content management systems. One example is the Knight Foundation-supported project Freedom Fone.

Image from Flickr user Andrew Michaels under Creative Commons license.

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