Human Language Technologies (HLT) – Telephony platform development

Many information services can be provided efficiently over the telephone, even in remote areas where access to alternative information infrastructure is limited. A number of the projects of the research group, such as the Lwazi and OpenPhone projects utilise a telephony platform to provide information services over standard telephony infrastructure. These information services also make use of novel speech technologies developed here at HLT, including both speech recognition and text-to-speech systems in the 11 official languages of South Africa.

The base of the current telephony platform is provided by the Asterisk software PBX (Private Branch Exchange), an open source telephony system developed by Digium. The speech technologies being developed are integrated at the level of the Asterisk software PBX. The base of the telephony platform first of all acts as an interface to the standard telephony world, and secondly provides a generic set of building blocks for creating telephony applications. These building blocks typically enable applications to interact with users by playing audio files, receiving touch-tone input, recording audio, etc. A few extra building blocks have been added by the HLT telephony platform developers. These new blocks enable applications to interact with users by making use of speech technologies such as speech recognition and text-to-speech.

An additional layer sits on top of the base of the telephony platform, which enables application developers to produce telephony-based applications without needing to know the details of the underlying telephony system. This application development layer is built upon the MobilED system. The initial development of the MobilED system was performed here at the Meraka Institute. Currently it is being used in a number of projects here, as well as worldwide.

The main enhancements being added to the standard Asterisk platform as part of this project, include:

• Integrating additional multilingual ASR and TTS services
• Adding additional monitoring and logging capability
• Adding an application development layer that makes it easier to develop telephony applications

Links:

Lwazi Telephony platform available for download

More information on the MobilED project

Visual authoring tool for Asterisk