RFC 6231
An Interactive Voice Response (IVR) Control Package for the Media Control Channel Framework
Internet Engineering Task Force (IETF) S. McGlashan Request for Comments: 6231 Hewlett-Packard Category: Standards Track T. Melanchuk ISSN: 2070-1721 Rainwillow C. Boulton NS-Technologies May 2011 An Interactive Voice Response (IVR) Control Package for the Media Control Channel FrameworkAbstract
This document defines a Media Control Channel Framework Package for Interactive Voice Response (IVR) dialog interaction on media connections and conferences. The package defines dialog management request elements for preparing, starting, and terminating dialog interactions, as well as associated responses and notifications. Dialog interactions are specified in a dialog language. This package defines a lightweight IVR dialog language (supporting prompt playback, runtime controls, Dual-Tone Multi-Frequency (DTMF) collection, and media recording) and allows other dialog languages to be used. The package also defines elements for auditing package capabilities and IVR dialogs. Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6231. Copyright Notice Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English.Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Conventions and Terminology . . . . . . . . . . . . . . . . . 8 3. Control Package Definition . . . . . . . . . . . . . . . . . 9 3.1. Control Package Name . . . . . . . . . . . . . . . . . . 9 3.2. Framework Message Usage . . . . . . . . . . . . . . . . . 9 3.3. Common XML Support . . . . . . . . . . . . . . . . . . . 10 3.4. CONTROL Message Body . . . . . . . . . . . . . . . . . . 10 3.5. REPORT Message Body . . . . . . . . . . . . . . . . . . . 10 3.6. Audit . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.7. Examples . . . . . . . . . . . . . . . . . . . . . . . . 11 4. Element Definitions . . . . . . . . . . . . . . . . . . . . . 11 4.1. <mscivr> . . . . . . . . . . . . . . . . . . . . . . . . 12 4.2. Dialog Management Elements . . . . . . . . . . . . . . . 14 4.2.1. <dialogprepare> . . . . . . . . . . . . . . . . . . . 18 4.2.2. <dialogstart> . . . . . . . . . . . . . . . . . . . . 20 4.2.2.1. <subscribe> . . . . . . . . . . . . . . . . . . . 24 4.2.2.1.1. <dtmfsub> . . . . . . . . . . . . . . . . . . 25 4.2.2.2. <stream> . . . . . . . . . . . . . . . . . . . . 26 4.2.2.2.1. <region> . . . . . . . . . . . . . . . . . . 27 4.2.2.2.2. <priority> . . . . . . . . . . . . . . . . . 27 4.2.3. <dialogterminate> . . . . . . . . . . . . . . . . . . 28 4.2.4. <response> . . . . . . . . . . . . . . . . . . . . . 28 4.2.5. <event> . . . . . . . . . . . . . . . . . . . . . . . 30 4.2.5.1. <dialogexit> . . . . . . . . . . . . . . . . . . 30 4.2.5.2. <dtmfnotify> . . . . . . . . . . . . . . . . . . 32 4.2.6. <params> . . . . . . . . . . . . . . . . . . . . . . 33 4.2.6.1. <param> . . . . . . . . . . . . . . . . . . . . . 33
4.3. IVR Dialog Elements . . . . . . . . . . . . . . . . . . . 34
4.3.1. <dialog> . . . . . . . . . . . . . . . . . . . . . . 35
4.3.1.1. <prompt> . . . . . . . . . . . . . . . . . . . . 38
4.3.1.1.1. <variable> . . . . . . . . . . . . . . . . . 39
4.3.1.1.1.1. Date Type . . . . . . . . . . . . . . . . 40
4.3.1.1.1.2. Time Type . . . . . . . . . . . . . . . . 41
4.3.1.1.1.3. Digits Type . . . . . . . . . . . . . . . 42
4.3.1.1.2. <dtmf> . . . . . . . . . . . . . . . . . . . 42
4.3.1.1.3. <par> . . . . . . . . . . . . . . . . . . . . 43
4.3.1.1.3.1. <seq> . . . . . . . . . . . . . . . . . . 45
4.3.1.2. <control> . . . . . . . . . . . . . . . . . . . . 46
4.3.1.3. <collect> . . . . . . . . . . . . . . . . . . . . 49
4.3.1.3.1. <grammar> . . . . . . . . . . . . . . . . . . 52
4.3.1.4. <record> . . . . . . . . . . . . . . . . . . . . 53
4.3.1.5. <media> . . . . . . . . . . . . . . . . . . . . . 57
4.3.2. Exit Information . . . . . . . . . . . . . . . . . . 59
4.3.2.1. <promptinfo> . . . . . . . . . . . . . . . . . . 59
4.3.2.2. <controlinfo> . . . . . . . . . . . . . . . . . . 59
4.3.2.2.1. <controlmatch> . . . . . . . . . . . . . . . 59
4.3.2.3. <collectinfo> . . . . . . . . . . . . . . . . . . 60
4.3.2.4. <recordinfo> . . . . . . . . . . . . . . . . . . 60
4.3.2.4.1. <mediainfo> . . . . . . . . . . . . . . . . . 61
4.4. Audit Elements . . . . . . . . . . . . . . . . . . . . . 61
4.4.1. <audit> . . . . . . . . . . . . . . . . . . . . . . . 61
4.4.2. <auditresponse> . . . . . . . . . . . . . . . . . . . 63
4.4.2.1. <codecs> . . . . . . . . . . . . . . . . . . . . 65
4.4.2.1.1. <codec> . . . . . . . . . . . . . . . . . . . 65
4.4.2.2. <capabilities> . . . . . . . . . . . . . . . . . 66
4.4.2.2.1. <dialoglanguages> . . . . . . . . . . . . . . 68
4.4.2.2.2. <grammartypes> . . . . . . . . . . . . . . . 68
4.4.2.2.3. <recordtypes> . . . . . . . . . . . . . . . . 68
4.4.2.2.4. <prompttypes> . . . . . . . . . . . . . . . . 68
4.4.2.2.5. <variables> . . . . . . . . . . . . . . . . . 69
4.4.2.2.5.1. <variabletype> . . . . . . . . . . . . . 69
4.4.2.2.6. <maxpreparedduration> . . . . . . . . . . . . 70
4.4.2.2.7. <maxrecordduration> . . . . . . . . . . . . . 70
4.4.2.3. <dialogs> . . . . . . . . . . . . . . . . . . . . 70
4.4.2.3.1. <dialogaudit> . . . . . . . . . . . . . . . . 71
4.5. Response Status Codes . . . . . . . . . . . . . . . . . . 71
4.6. Type Definitions . . . . . . . . . . . . . . . . . . . . 77
4.6.1. Boolean . . . . . . . . . . . . . . . . . . . . . . . 77
4.6.2. DTMFChar . . . . . . . . . . . . . . . . . . . . . . 77
4.6.3. DTMFString . . . . . . . . . . . . . . . . . . . . . 77
4.6.4. Non-Negative Integer . . . . . . . . . . . . . . . . 77
4.6.5. Positive Integer . . . . . . . . . . . . . . . . . . 77
4.6.6. String . . . . . . . . . . . . . . . . . . . . . . . 78
4.6.7. Time Designation . . . . . . . . . . . . . . . . . . 78
4.6.8. Percentage . . . . . . . . . . . . . . . . . . . . . 78
4.6.9. URI . . . . . . . . . . . . . . . . . . . . . . . . . 78
4.6.10. MIME Media Type . . . . . . . . . . . . . . . . . . . 78
4.6.11. Language Identifier . . . . . . . . . . . . . . . . . 78
4.6.12. DateTime . . . . . . . . . . . . . . . . . . . . . . 79
5. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 79
6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 105
6.1. AS-MS Dialog Interaction Examples . . . . . . . . . . . . 105
6.1.1. Starting an IVR Dialog . . . . . . . . . . . . . . . 105
6.1.2. IVR Dialog Fails to Start . . . . . . . . . . . . . . 106
6.1.3. Preparing and Starting an IVR Dialog . . . . . . . . 107
6.1.4. Terminating a Dialog . . . . . . . . . . . . . . . . 108
6.2. IVR Dialog Examples . . . . . . . . . . . . . . . . . . . 108
6.2.1. Playing Announcements . . . . . . . . . . . . . . . . 109
6.2.2. Prompt and Collect . . . . . . . . . . . . . . . . . 109
6.2.3. Prompt and Record . . . . . . . . . . . . . . . . . . 111
6.2.4. Runtime Controls . . . . . . . . . . . . . . . . . . 112
6.2.5. Subscriptions and Notifications . . . . . . . . . . . 113
6.2.6. Dialog Repetition until DTMF Collection Complete . . 113
6.3. Other Dialog Languages . . . . . . . . . . . . . . . . . 114
6.4. Foreign Namespace Attributes and Elements . . . . . . . . 115
7. Security Considerations . . . . . . . . . . . . . . . . . . . 116
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 119
8.1. Control Package Registration . . . . . . . . . . . . . . 119
8.2. URN Sub-Namespace Registration . . . . . . . . . . . . . 120
8.3. XML Schema Registration . . . . . . . . . . . . . . . . . 120
8.4. MIME Media Type Registration for
application/msc-ivr+xml . . . . . . . . . . . . . . . . . 120
8.5. IVR Prompt Variable Type Registration Information . . . . 121
9. Using VoiceXML as a Dialog Language . . . . . . . . . . . . . 122
9.1. Preparing a VoiceXML Dialog . . . . . . . . . . . . . . . 122
9.2. Starting a VoiceXML Dialog . . . . . . . . . . . . . . . 123
9.2.1. Session Protocol Information . . . . . . . . . . . . 124
9.2.2. Session Media Stream Information . . . . . . . . . . 125
9.2.3. Session Parameter Information . . . . . . . . . . . . 127
9.3. Terminating a VoiceXML Dialog . . . . . . . . . . . . . . 128
9.4. Exiting a VoiceXML Dialog . . . . . . . . . . . . . . . . 128
9.5. Call Transfer . . . . . . . . . . . . . . . . . . . . . . 129
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 130
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 130
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 130
12.1. Normative References . . . . . . . . . . . . . . . . . . 130
12.2. Informative References . . . . . . . . . . . . . . . . . 132
1. Introduction
The Media Control Channel Framework [RFC6230] provides a generic approach for establishment and reporting capabilities of remotely initiated commands. The Channel Framework -- an equivalent term for the Media Control Channel Framework -- utilizes many functions provided by the Session Initiation Protocol (SIP) [RFC3261] for the rendezvous and establishment of a reliable channel for control interactions. The Control Framework also introduces the concept of a Control Package. A Control Package is an explicit usage of the Control Framework for a particular interaction set. This document defines a Control Package for Interactive Voice Response (IVR) dialogs on media connections and conferences. The term 'dialog' in this document refers to an IVR dialog and is completely unrelated to the notion of a SIP dialog. The term 'IVR' is used in its inclusive sense, allowing media other than voice for dialog interaction. The package defines dialog management request elements for preparing, starting, and terminating dialog interactions, as well as associated responses and notifications. Dialog interactions are specified using a dialog language where the language specifies a well-defined syntax and semantics for permitted operations (play a prompt, record input from the user, etc.). This package defines a lightweight IVR dialog language (supporting prompt playback, runtime controls, DTMF collection, and media recording) and allows other dialog languages to be used. These dialog languages are specified inside dialog management elements for preparing and starting dialog interactions. The package also defines elements for auditing package capabilities and IVR dialogs. This package has been designed to satisfy IVR requirements documented in "Media Server Control Protocol Requirements" [RFC5167] -- more specifically, REQ-MCP-28, REQ-MCP-29, and REQ-MCP-30. It achieves this by building upon two major approaches to IVR dialog design. These approaches address a wide range of IVR use cases and are used in many applications that are extensively deployed today. First, the package is designed to provide the major IVR functionality of SIP media server languages such as netann [RFC4240], Media Server Control Markup Language (MSCML) [RFC5022], and Media Server Markup Language (MSML) [RFC5707], which themselves build upon more traditional non-SIP languages ([H.248.9], [RFC2897]). A key differentiator is that this package provides IVR functionality using the Channel Framework. Second, its design is aligned with key concepts of the web model as defined in W3C Voice Browser languages. The key dialog management mechanism is closely aligned with Call Control XML (CCXML) [CCXML10].
The dialog functionality defined in this package can be largely seen as a subset of VoiceXML ([VXML20], [VXML21]): where possible, basic prompting, DTMF collection, and media recording features are incorporated, but not any advanced VoiceXML constructs (such as <form>, its interpretation algorithm, or a dynamic data model). As W3C develops VoiceXML 3.0 [VXML30], we expect to see further alignment, especially in providing a set of basic independent primitive elements (such as prompt, collect, record, and runtime controls) that can be reused in different dialog languages. By reusing and building upon design patterns from these approaches to IVR languages, this package is intended to provide a foundation that is familiar to current IVR developers and sufficient for most IVR applications, as well as a path to other languages that address more advanced applications. This Control Package defines a lightweight IVR dialog language. The scope of this dialog language is the following IVR functionality: o playing one or more media resources as a prompt to the user o runtime controls (including VCR controls like speed and volume) o collecting DTMF input from the user according to a grammar o recording user media input Out of scope for this dialog language are more advanced functions including ASR (Automatic Speech Recognition), TTS (Text-to-Speech), fax, automatic prompt recovery ('media fallback'), and media transformation. Such functionality can be addressed by other dialog languages (such as VoiceXML) used with this package, extensions to this package (addition of foreign elements or attributes from another namespace), or other Control Packages. The functionality of this package is defined by messages, containing XML [XML] elements, transported using the Media Control Channel Framework. The XML elements can be divided into three types: dialog management elements; a dialog element that defines a lightweight IVR dialog language used with dialog management elements; and finally, elements for auditing package capabilities as well as dialogs managed by the package. Dialog management elements are designed to manage the general lifecycle of a dialog. Elements are provided for preparing a dialog, starting the dialog on a conference or connection, and terminating execution of a dialog. Each of these elements is contained in a Media Control Channel Framework CONTROL message sent to the media
server. When the appropriate action has been executed, the media server sends a REPORT message (or a 200 response to the CONTROL message if it can execute in time) with a response element indicating whether or not the operation was successful (e.g., if the dialog cannot be started, then the error is reported in this response). Once a dialog has been successfully started, the media server can send further event notifications in a framework CONTROL message. This package defines two event notifications: a DTMF event indicating the DTMF activity, and a dialogexit event indicating that the dialog has exited. If the dialog has executed successfully, the dialogexit event includes information collected during the dialog. If an error occurs during execution (e.g., a media resource failed to play, no recording resource available, etc.), then error information is reported in the dialogexit event. Once a dialogexit event is sent, the dialog lifecycle is terminated. The dialog management elements for preparing and starting a dialog specify the dialog using a dialog language. A dialog language has well-defined syntax and semantics for defined dialog operations. Typically, dialog languages are written in XML where the root element has a designated XML namespace and, when used as standalone documents, have an associated MIME media type. For example, VoiceXML is an XML dialog language with the root element <vxml> with the designated namespace 'http://www.w3.org/2001/vxml' and standalone documents are associated with the MIME media type 'application/ voicexml+xml' [RFC4267]. This Control Package defines its own lightweight IVR dialog language. The language has a root element (<dialog>) with the same designated namespace as used for other elements defined in this package (see Section 8.2). The root element contains child elements for playing prompts to the user, specifying runtime controls, collecting DTMF input from the user, and recording media input from the user. The child elements can co-occur so as to provide 'play announcement', 'prompt and collect', as well as 'prompt and record' functionality. The dialog management elements for preparing and starting a dialog can specify the dialog language either by including inline a fragment with the root element or by referencing an external dialog document. The dialog language defined in this package is specified inline. Other dialog languages, such as VoiceXML, can be used by referencing an external dialog document. The document is organized as follows. Section 3 describes how this Control Package fulfills the requirements for a Media Control Channel Framework Control Package. Section 4 describes the syntax and semantics of defined elements, including dialog management (Section 4.2), the IVR dialog element (Section 4.3), and audit
elements (Section 4.4). Section 5 describes an XML schema for these elements and provides extensibility by allowing attributes and elements from other namespaces. Section 6 provides examples of package usage. Section 7 describes important security considerations for use of this Control Package. Section 8 provides information on IANA registration of this Control Package, including its name, XML namespace, and MIME media type. It also establishes a registry for prompt variables. Finally, Section 9 provides additional information on using VoiceXML when supported as an external dialog language.2. Conventions and Terminology
In this document, BCP 14 [RFC2119] defines the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL". In addition, BCP 15 indicates requirement levels for compliant implementations. The following additional terms are defined for use in this document: Dialog: A dialog performs media interaction with a user following the concept of an IVR (Interactive Voice Response) dialog (this sense of 'dialog' is completely unrelated to a SIP dialog). A dialog is specified as inline XML or via a URI reference to an external dialog document. Traditional IVR dialogs typically feature capabilities such as playing audio prompts, collecting DTMF input, and recording audio input from the user. More inclusive definitions include support for other media types, runtime controls, synthesized speech, recording and playback of video, recognition of spoken input, and mixed initiative conversations. Application Server: A SIP [RFC3261] application server (AS) hosts and executes services such as interactive media and conferencing in an operator's network. An AS influences and impacts the SIP session, in particular by terminating SIP sessions on a media server, which is under its control. Media Server: A media server (MS) processes media streams on behalf of an AS by offering functionality such as interactive media, conferencing, and transcoding to the end user. Interactive media functionality is realized by way of dialogs that are initiated by the application server.
3. Control Package Definition
This section fulfills the mandatory requirement for information that MUST be specified during the definition of a Control Framework Package, as detailed in Section 7 of [RFC6230].3.1. Control Package Name
The Control Framework requires a Control Package to specify and register a unique name. The name of this Control Package is "msc-ivr/1.0" (Media Server Control - Interactive Voice Response - version 1.0). Its IANA registration is specified in Section 8.1. Since this is the initial ("1.0") version of the Control Package, there are no backwards-compatibility issues to address.3.2. Framework Message Usage
The Control Framework requires a Control Package to explicitly detail the CONTROL messages that can be used as well as provide an indication of directionality between entities. This will include which role type is allowed to initiate a request type. This package specifies Control and response messages in terms of XML elements defined in Section 4, where the message bodies have the MIME media type defined in Section 8.4. These elements describe requests, responses, and notifications and all are contained within a root <mscivr> element (Section 4.1). In this package, the MS operates as a Control Server in receiving requests from, and sending responses to, the AS (operating as Control Client). Dialog management requests and responses are defined in Section 4.2. Audit requests and responses are defined in Section 4.4. Dialog management and audit responses are carried in a framework 200 response or REPORT message bodies. This package's response codes are defined in Section 4.5. Note that package responses are different from framework response codes. Framework error response codes (see Section 7 of [RFC6230]) are used when the request or event notification is invalid; for example, a request is invalid XML (400), or not understood (500). The MS also operates as a Control Client in sending event notification to the AS (Control Server). Event notifications (Section 4.2.5) are carried in CONTROL message bodies. The AS MUST respond with a Control Framework 200 response.
3.3. Common XML Support
The Control Framework requires a Control Package definition to specify if the attributes for media dialog or conference references are required. This package requires that the XML schema in Section A.1 of [RFC6230] MUST be supported for media dialogs and conferences. The package uses "connectionid" and "conferenceid" attributes for various element definitions (Section 4). The XML schema (Section 5) imports the definitions of these attributes from the framework schema.3.4. CONTROL Message Body
The Control Framework requires a Control Package to define the control body that can be contained within a CONTROL command request and to indicate the location of detailed syntax definitions and semantics for the appropriate body types. When operating as Control Server, the MS receives Control message bodies with the MIME media type defined in Section 8.4 and containing an <mscivr> element (Section 4.1) with either a dialog management or audit request child element. The following dialog management request elements are carried in CONTROL message bodies to the MS: <dialogprepare> (Section 4.2.1), <dialogstart> (Section 4.2.2), and <dialogterminate> (Section 4.2.3) elements. The <audit> request element (Section 4.4.1) is also carried in CONTROL message bodies. When operating as Control Client, the MS sends CONTROL messages with the MIME media type defined in Section 8.4 and a body containing an <mscivr> element (Section 4.1) with a notification <event> child element (Section 4.2.5).3.5. REPORT Message Body
The Control Framework requires a Control Package definition to define the REPORT body that can be contained within a REPORT command request, or that no report package body is required. This section indicates the location of detailed syntax definitions and semantics for the appropriate body types.
When operating as Control Server, the MS sends REPORT bodies with the MIME media type defined in Section 8.4 and containing a <mscivr> element (Section 4.1) with a response child element. The response element for dialog management requests is a <response> element (Section 4.2.4). The response element for an audit request is an <auditresponse> element (Section 4.4.2).3.6. Audit
The Control Framework encourages Control Packages to specify whether auditing is available, how it is triggered, as well as the query/ response formats. This Control Package supports auditing of package capabilities and dialogs on the MS. An audit request is carried in a CONTROL message (see Section 3.4) and an audit response in a REPORT message (or a 200 response to the CONTROL if it can execute the audit in time) (see Section 3.5). The syntax and semantics of audit request and response elements are defined in Section 4.4.3.7. Examples
The Control Framework recommends Control Packages to provide a range of message flows that represent common flows using the package and this framework document. This Control Package provides examples of such message flows in Section 6.
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