Using Tcl Scripts and VoiceXML

Cisco voice gateways have the ability to support interactive voice response (IVR) and advanced call-handling applications using Toolkit Command Language (Tcl) or VoiceXML (sometimes referenced as VXML). Tcl and VoiceXML are scripting languages that allow the gateway to provide specialized call treatment, such as playing audio prompts and accepting user input using dual-tone multifrequency (DTMF) tones.

Dr. John Ousterhout developed the Tcl script language at the University of California, Berkeley. Cisco voice gateways run Tcl IVR 2.0, which is based on Tcl with a proprietary Cisco application programming interface (API). On the Cisco website, you will sometimes see Tcl referred to as "TCL," but the official name is Tcl.

VoiceXML is a standards-based markup language for voice browsers. VoiceXML can utilize existing web server and application logic, which can reduce development time and expense.

This chapter helps you to do the following:

• Understand how Tcl and VoiceXML applications operate
• Understand the difference between Tcl and VoiceXML applications
• Review sample Tcl scripts that are available from Cisco
• Implement Tcl scripts in a voice gateway
• Create audio files for use with Tcl scripts
• Verify and troubleshoot applications