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rfc:rfc2897

Network Working Group D. Cromwell Request for Comments: 2897 Nortel Networks Category: Informational August 2000

            Proposal for an MGCP Advanced Audio Package

Status of this Memo

 This memo provides information for the Internet community.  It does
 not specify an Internet standard of any kind.  Distribution of this
 memo is unlimited.

Copyright Notice

 Copyright (C) The Internet Society (2000).  All Rights Reserved.

Abstract

 This document is a proposal to add a new event/signal package to the
 MGCP (Media Gateway Control Protocol) protocol to control an ARF
 (Audio Resource Function) which may reside on a Media Gateway or
 specialized Audio Server.
 This event package provides support for the standard IVR (Interactive
 Voice Response) operations of PlayAnnouncement, PlayCollect, and
 PlayRecord.  It supports direct references to simple audio as well as
 indirect references to simple and complex audio. It provides audio
 variables, control of audio interruptibility, digit buffer control,
 special key sequences, and support for reprompting during data
 collection.  It also provides an arbitrary number of user defined
 qualifiers to be used in resolving complex audio structures.  For
 example, the user could define qualifiers for any or all of the
 following: language, accent, audio file format, gender, speaker, or
 customer.

Cromwell Informational [Page 1] RFC 2897 MGCP Advanced Audio Package August 2000

Table of Contents

 1. Introduction ................................................  2
 1.1. Audio Segments ............................................  3
 1.1.1. Sequences And Sets ......................................  3
 1.1.2. Segment Types ...........................................  4
 2. Advanced Audio Package ......................................  5
 3. Events ......................................................  5
 4. Event Parameters ............................................  7
 5. Return Parameters ...........................................  7
 6. Variables ................................................... 14
 7. Selectors ................................................... 17
 8. Aliases ..................................................... 18
 9. Examples .................................................... 21
 10. Formal Syntax Description .................................. 22
 11. References ................................................. 22
 12. Formal Syntax Description .................................. 25
 13. References ................................................. 32
 14. Author's Address ........................................... 33
 15. Full Copyright Statement ................................... 34

1. Introduction

 The following syntax supports both simple and complex audio
 structures.  A simple audio structure might be a single announcement
 such as "Welcome to Bell South's Automated Directory Assistance
 Service".  A more complex audio structure might consist of an
 announcement followed by voice variable followed by another
 announcement, for example "There are thirty seven minutes remaining
 on your prepaid calling card," where "There are" is a prompt, the
 number of minutes is a voice variable, and "minutes remaining on your
 prepaid calling card" is another prompt.
 It is also possible to define complex audio structures that are
 qualified by user defined selectors such as language, audio file
 format, gender, accent, customer, or voice talent.  For instance, if
 the above example were qualified by language and accent selectors, it
 would be possible to play "There are thirty seven minutes remaining
 on your prepaid calling card" in English spoken with a southern
 accent or in English spoken with a mid-western accent, providing that
 the audio to support this had been provisioned.
 There are two methods of specifying complex audio.  The first is to
 directly reference the individual components.  This requires a
 complete description of each component to be specified via the
 protocol.  The second method is to provision the components on the
 Audio Server as a single entity and to export a reference to that
 entity to the call agent.  In this case, only the reference (plus any

Cromwell Informational [Page 2] RFC 2897 MGCP Advanced Audio Package August 2000

 dynamic data required, such as a variable data) is passed via the
 protocol, and no specification of individual components is necessary.
 The Audio Server Package provides significant functionality most of
 which is controlled via protocol parameters.  Most parameters are
 optional, and where ever possible default to reasonable values.  An
 audio application that references to provisioned, complex audio
 structures, and which takes advantage of parameter optionality and
 defaults, can specify audio events using a minimum of syntax.

1.1. Background

 The next two sections contain background information which may be
 helpful in understanding the syntax.

1.1.1. Sequence And Sets

 The syntax supports abstractions of set and sequence for storing and
 referencing audio data.
 A sequence is a provisioned sequence of one or more audio segments.
 Component segments are not necessarily all of the same type.  Every
 sequence is assigned a unique segment id.  On playback, a sequence id
 reference is deconstructed into its individual parts, each of which
 is played in order.
 A set is a provisioned collection of audio segments with an
 associated selector.  On playback, the selector value is resolved to
 a particular set element.  Selector types are supported by the
 syntax, but individual selector types are not defined in the syntax
 except for the pre-defined language selector; they are instead
 defined by the user (i.e.  provisioner).  A user could define one or
 more of the following selector types: language, accent, audio file
 format, gender, accent, customer, or day of the week.  For each
 selector type, the user must define a range of valid values.  The
 user may also choose to define a default value.  At runtime if a
 selector value is not supplied the default value is used.
 For example, to support an application which plays a particular piece
 of audio in either English, French, or Russian, a provisioner would
 define a set with the pre-defined selector, "Lang", and would define
 three possible values for that selector, "eng", "fra", and "rus".
 The provisioner would then provision three recordings of the prompt,
 one in each language, and would associate the French recording with
 the "fra" selector value, etc.  The provisioner also could define a
 default value of the selector when no selector value is supplied,
 "eng" for instance.  The entire set would be assigned a unique
 segment id.

Cromwell Informational [Page 3] RFC 2897 MGCP Advanced Audio Package August 2000

 At runtime a reference to the set with the selector set to "rus"
 would result in the Russian version of the prompt being played.  A
 reference to the set with no selector would result in the English
 version of the prompt being played since English has been set as the
 default selector value.
 Nested definition of both sets and sequences is allowed, i.e. it
 legal to define a set of sets or a sequence of sequences.  In
 addition, audio structures may also be specified by intermixing sets
 and sequences, and it is possible to specify a set of sequences or a
 sequence containing one or more set elements.  Direct or transitive
 definition of a set or segment in terms of itself is not allowed.

1.1.2. Segment Types

 The syntax supports the following segment types:
    RECORDING:  A reference by unique id to a single piece of recorded
    audio.
    RECORDINGs may be provisioned or they may be made during the
    course of a call.  A RECORDING made during the course of a call
    can be temporary or persistent.  A temporary RECORDING lasts only
    for the life of the call during which it was recorded.  A
    persistent RECORDING lasts beyond the live of the call during
    which it was recorded.
    A provisioned RECORDING may be replaced (or overridden) by a
    persistent RECORDING.  A reference to the id of the provisioned
    RECORDING will then resolve to the persistent RECORDING.  The
    overriding persistent audio can subsequently be deleted and the
    original provisioned audio can be restored.
    A provisioned RECORDING may be overridden more than once.  In this
    case, the id of the provisioned RECORDING refers to the latest
    overriding RECORDING.  When the overriding RECORDING is deleted,
    the original provisioned RECORDING is restored, even if the
    segment has been overridden multiple times.
    TEXT:  A reference to a block of text to be converted to speech or
    to be displayed on a device. Reference may be by unique id to a
    block of provisioned text or by direct specification of text in a
    parameter.
    SILENCE:  A specification of a length of silence to be played in
    units of 100 milliseconds.

Cromwell Informational [Page 4] RFC 2897 MGCP Advanced Audio Package August 2000

    TONE: The specification of a tone to be played by algorithmic
    generation.  Most tones however will probably be recorded, not
    generated. Exact specification of this segment type is tbd.
    VARIABLE:  The specification of a voice variable by the parameters
    of type, subtype, and value.  Specification of variables is
    considered in more detail in a subsequent section of this
    document.
    SEQUENCE: A reference by unique id to a provisioned sequence of
    mixed RECORDING, TEXT, SILENCE, TONE, VARIABLE, SET, or SEQUENCE
    segments. Nested definition of SEQUENCE segments is allowed.
    Direct or transitive definition of a SEQUENCE segment in terms of
    itself is not allowed.
    SET:  A  reference by unique id to a provisioned set of segments.
    The intended and recommended use of the SET type is that all
    segments in the set should be semantically equivalent, however
    there is no real way of enforcing this restriction either in the
    protocol or in provisioning.  Every set has an associated selector
    which is used at runtime to resolve the set reference to a
    specific element of the set.  The elements of a set may one of the
    following segment types:  RECORDING, TEXT, TONE, SILENCE,
    SEQUENCE, or SET.  Specific selector types are not specified by
    the protocol and must be defined by the user.  Nested definition
    of SET segments is allowed. Direct or transitive definition of a
    SET segment in terms of itself is not allowed.

2. Advanced Audio Package

 Package Name: AU
 This package defines events and signals for an ARF package for an
 Audio Server Media Gateway.

3. Events

| Symbol | Definition | R | S Duration | |||||

pa(parms) PlayAnnouncement TO variable
pc(parms) PlayCollect TO variable
pr(parms) PlayRecord TO variable
es(parm) EndSignal BR
oc(parms) OperationComplete x
of(parms) OperationFailed x
||
Parameters
| | Symbol | Definition | pl | pc | pr | |__| | an | announcement | x | | | | ip | initial prompt | | x | x | | rp | reprompt | | x | x | | nd | no digits reprompt | | x | | | ns | no speech reprompt | | | x | | fa | failure announcement | | x | x | | sa | success announcement | | x | x | | ni | non-interruptible play | | x | x | | it | iterations | x | | | | iv | interval | x | | | | du | duration | x | | | | sp | speed | x | x | x | | vl | volume | x | x | x | | cb | clear digit buffer | | x | x | | mx | maximum # of digits | | x | | | mn | minimum # of digits | | x | | | dp | digit pattern | | x | | | fdt | first digit timer | | x | | | idt | inter digit timer | | x | | | edt | extra digit timer | | x | | | prt | pre-speech timer | | | x | | pst | post-speech timer | | | x | | rlt | total recording length timer | | | x | | rsk | restart key | | x | x | | rik | reinput key | | x | x | | rtk | return key | | x | x | | psk | position key | | x | x | | stk | stop key | | x | x | | sik | start input key | | x | | | eik | end input key | | x | x | | iek | include end input key | | x | | | na | number of attempts | | x | x | |__| Parameters to the Advanced Audio Package events are defined as follows: Announcement: An announcement to be played. Consists of one or more audio segments. Cromwell Informational [Page 8] RFC 2897 MGCP Advanced Audio Package August 2000 Initial Prompt: The initial announcement prompting the user to either enter DTMF digits or to speak. Consists of one or more audio segments. If not specified (the default), the event immediately begins digit collection or recording. Reprompt: Played after the user has made an error such as entering an invalid digit pattern or not speaking. Consists of one or more audio segments. Defaults to the Initial Prompt. No Digits Reprompt: Played after the user has failed to enter a valid digit pattern during a PlayCollect event. Consists of one or more audio segments. Defaults to the Reprompt. No Speech Reprompt: Played after the user has failed to speak during a PlayRecord event. Consists of one or more audio segments. Defaults to the Reprompt. Failure Announcement: Played when all data entry attempts have failed. Consists of one or more audio segments. No default. Success Announcement: Played when data collection has succeeded. Consists of one or more audio segments. No default. Non-Interruptible Play: If set to true, initial prompt is not interruptible by either voice or digits. Defaults to false. Valid values are the text strings "true" and "false". Iterations: The maximum number of times an announcement is to be played. A value of minus one (-1) indicates the announcement is to be repeated forever. Defaults to one (1). Cromwell Informational [Page 9] RFC 2897 MGCP Advanced Audio Package August 2000 Interval: The interval of silence to be inserted between iterative plays. Specified in units of 100 milliseconds. Defaults to 10 (1 second). Duration: The maximum amount of time to play and possibly replay an announcement. Takes precedence over iteration and interval. Specified in units of 100 milliseconds. No default. Speed: The relative playback speed of announcement specifiable as a positive or negative percentage of the original playback speed. Volume: The relative playback volume of announcement specifiable as a positive or negative decibel variation from the original play-back volume. Clear Digit Buffer: If set to true, clears the digit buffer before playing the initial prompt. Defaults to false. Valid values are the text strings "true" and "false". Maximum # Of Digits: The maximum number of digits to collect. Defaults to one. This parameter should not be specified if the Digit Pattern parameter is present. Minimum # Of Digits: The minimum number of digits to collect. Defaults to one. This parameter should not be specified if the Digit Pattern parameter is present. Digit Pattern: A legal digit map as described in section 7.1.14 of the Megaco protocol [6] using the DTMF mappings associated with the Megaco DTMF Detection Package described in the Megaco protocol document Cromwell Informational [Page 10] RFC 2897 MGCP Advanced Audio Package August 2000 [6]. This parameter should not be specified if one or both of the Minimum # Of Digits parameter and the Maximum Number Of Digits parameter is present. First Digit Timer: The amount of time allowed for the user to enter the first digit. Specified in units of 100 milliseconds. 50 (5 seconds). Inter Digit Timer: The amount of time allowed for the user to enter each subsequent digit. Specified units of 100 milliseconds seconds. Defaults to 30 (3 seconds). Extra Digit Timer: The amount of time to wait for a user to enter a final digit once the maximum expected amount of digits have been entered. Typically this timer is used to wait for a terminating key in applications where a specific key has been defined to terminate input. Specified in units of 100 milliseconds. If not specified, this timer is not activated. Pre-speech Timer: The amount of time to wait for the user to initially speak. Specified in units of 100 milliseconds. Defaults to 30 (3 seconds). Post-speech Timer: The amount of silence necessary after the end of the last speech segment for the recording to be considered complete. Specified in units of 100 milliseconds. Defaults to 20 (2 seconds). Recording Length Timer: The maximum allowable length of the recording, not including pre or post speech silence. Specified in units of 100 milliseconds. This parameter is mandatory. Restart Key: Defines a key sequence consisting of a command key optionally followed by zero or more keys. This key sequence has the following action: discard any digits collected or recording in progress, replay the prompt, and resume digit collection or Cromwell Informational [Page 11] RFC 2897 MGCP Advanced Audio Package August 2000 recording. No default. An application that defines more than one command key sequence, will typically use the same command key for all command key sequences. If more than one command key sequence is defined, then all key sequences must consist of a command key plus at least one other key. Reinput Key: Defines a key sequence consisting of a command key optionally followed by zero or more keys. This key sequence has the following action: discard any digits collected or recordings in progress and resume digit collection or recording. No default. An application that defines more than one command key sequence, will typically use the same command key for all command key sequences. If more than one command key sequence is defined, then all key sequences must consist of a command key plus at least one other key. Return Key: Defines a key sequence consisting of a command key optionally followed by zero or more keys. This key sequence has the following action: terminate the current event and any queued event and return the terminating key sequence to the call processing agent. No default. An application that defines more than one command key sequence, will typically use the same command key for all command key sequences. If more than one command key sequence is defined, then all key sequences must consist of a command key plus at least one other key. Position Key: Defines a key with the following action. Stop playing the current announcement and resume playing at the beginning of the first, last, previous, next, or the current segment of the announcement. No default. The actions for the position key are fst, lst, prv, nxt, and cur. Stop Key: Defines a key with the following action. Terminate playback of the announcement. No default. Start Input Keys: Defines a set of keys that are acceptable as the first digit collected. This set of keys can be specified to interrupt a playing announcement or to not interrupt a playing announcement. Cromwell Informational [Page 12] RFC 2897 MGCP Advanced Audio Package August 2000 The default key set is 0-9. The default behavior is to interrupt a playing announcement when a Start Input Key is pressed. This behavior can be overidden for the initial prompt only by using the ni (Non-Interruptible Play) parameter. Specification is a list of keys with no separators, e.g. 123456789#. End Input Key: Specifies a key that signals the end of digit collection or voice recording. The default end input key is the # key. To specify that no End Input Key be used the parameter is set to the string "null". The default behavior not to return the End Input Key in the digits returned to the call agent. This behavior can be overidden by the Include End Input Key (eik) parameter. Include End Input Key: By default the End Input Key is not included in the collected digits returned to the call agent. If this parameter is set to "true" then the End Input Key will be returned with the collected digits returned to the call agent. Default is "false". Number Of Attempts: The number of attempts the user needed to enter a valid digit pattern or to make a recording. Defaults to 1. Also used as a return parameter to indicate the number of attempts the user made. Record Persistent Audio: If set to true, the recording that is made is persistent instead of temporary. Defaults to false. Valid values are the text strings "true" and "false". Delete Persistent Audio Indicates that the specified persistent audio segment is to be deleted. This parameter is carried by the PlayRecord event, although nothing is either played or recorded in this case. Override Audio: Indicates that the specified provisioned audio segment is to be overridden with a persistent audio segment to be recorded in the PlayRecord operation that carries this parameter. Cromwell Informational [Page 13] RFC 2897 MGCP Advanced Audio Package August 2000 Restore Audio: Indicates that the provisioned audio segment originally associated with the specified segment id is to be restored and that the overriding persistent audio is to be deleted. This parameter is carried by the PlayRecord event, although nothing is either played or recorded in this case. 6. Return Parameters Each event has an associated set of possible return parameters which are listed in the following tables. | Return Parameters | |_
Symbol Definition pl pc pr
_|||_|_
vi voice interrupt x
ik interrupting key sequence x
ap amount played x x
na number of attempts x x
dc digits collected x
ri recording id x
rc return code x x x
_|||_|_
 Voice Interrupted:
    Set to "true" if the initial prompt of a PlayRecord operation was
    interrupted by voice.  Defaults to "false".
 Interrupting Key Sequence:
    The key or key sequence that interrupted the initial prompt of a
    PlayCollect specified using the digit map characters "0" through
    "9" and "A" through "F" as defined in the DTMF Detection Package
    in the Megaco protocol document [6].
 Amount Played:
    The length played of an initial prompt if the prompt was
    interrupted, in 100 ms units.

Cromwell Informational [Page 14] RFC 2897 MGCP Advanced Audio Package August 2000

 Number Of Attempts:
    The number of attempts the user needed to enter a valid digit
    pattern or to make a recording.  Defaults to 1.  Also used as an
    input parameter to specify the number of attempts the user will be
    allowed to enter a valid digit pattern or make a recording.
 Digits Collected:
    The DTMF digits that were collected during a PlayCollect operation
    specified using the digit map characters "0" through "9" and "A"
    through "F" as defined in the DTMF Detection Package in the Megaco
    protocol document [6].
 Recording ID:
    A 32 bit binary integer assigned to audio recorded during the Play
    Record operation.
 Return Code:
    A return code giving the final status  of  the  operation.   Two
    ranges are defined:
                 _________________________________
                 | Range  |        Meaning        |
                 |________|_______________________|
                 |100-199 | successful completion |
                 |300-399 | error                 |
                 |________|_______________________|

Cromwell Informational [Page 15] RFC 2897 MGCP Advanced Audio Package August 2000

 The following return codes are define:

Return Code Meaning
| | 100 | Success | | 300 | Unspecified failure | | 301 | Bad audio ID | | 302 | Bad selector type | | 303 | Bad selector value | | 304 | Variable type not supported | | 305 | Variable subtype not supported | | 306 | Invalid variable name | | 307 | Variable value out of range | | 308 | Inconsistent variable specification | | 309 | Alias not found | | 310 | Extra sequence data | | 311 | Missing sequence data | | 312 | Mismatch between play specification and provisioned data | | 313 | Language not set | | 314 | Remove override error | | 315 | Override error | | 316 | Delete audio error | | 317 | Unable to record temporary audio | | 318 | Unable to delete temporary audio | | 319 | Unable to record persistent audio | | 320 | Unable to delete persistent audio | | 321 | Unable to override non-existent segment id | | 322 | Unable to remove override from non-existent segment id | | 323 | Provisioning error | | 324 | Unspecified hardware failure | | 325 | Syntax error | | 326 | No digits | | 327 | No speech | | 328 | Spoke too long | | 329 | Digit pattern not matched | | 330 | Max attempts exceeded | ||
 Here are some examples of how the return parameters are used:
 The PlayAnnouncement event completed successfully:
    O: AU/oc(rc=100)
 The PlayAnnouncement event failed because an alias was not found:
    O: AU/of(rc=309)

Cromwell Informational [Page 16] RFC 2897 MGCP Advanced Audio Package August 2000

 The PlayCollect event completed successfully on the user's second
 attempt when the user entered the digits 04375182:
    O: AU/oc(rc=100 na=2 dc=04375182)
 The PlayRecord event was successful on the user's first attempt; the
 id of the recording made by the user is 983:
    O: AU/oc(rc=100 na=1 ri=983)

7. Segment Descriptors

 Segment descriptors are used with the an, ip, rp, nd, ns, fa, and sa
 parameters to define the segments that make up an announcement.

Segment Descriptors
_| | Symbol | Definition | ||
32 bit binary number segment identifier
ts text to speech
dt display text
si silence
to tone
vb variable
| Segment Identifier: A 32 bit binary integer identifying a provisioned entity such as a recording, set, sequence, etc. Text To Speech: Specifies a text string to be converted to speech. Display Text: Specifies a text string to be displayed on a device. Silence: Specifies a length of silence to be played in units of 100 milliseconds. Cromwell Informational [Page 17] RFC 2897 MGCP Advanced Audio Package August 2000 Tone: Specifies a tone to be played by algorithmic generation. Exact specification of this parameter is tbd. Most tones will likely be recorded, not generated. Variable: Specifies a voice variable by type, subtype, and value. Variables are more completely defined in a subsequent section of the document. 8. Variables The syntax supports two kinds of variables. Embedded embedded variables are variables that have been provisioned as part of a segment. Standalone variables are completely specified in the protocol message. Typically embedded variables are provisioned along with recorded speech, e.g. "A representative will be with you in approximately 5 minutes. If you would prefer to leave a voice message, press 1 now". where the variable is the number of minutes. This kind of variable is often referred to as an embedded variable. Variables are specified by the following parameters: type, subtype, and value. Variable types include Date, Money, Number, Time, etc. Subtype is a refinement of type. For example the variable type Money might have an associated range of subtypes such as Dollar, Rupee, Dinar, etc. Not all variables require a subtype, and for these variables the subtype parameter should be set to null. For embedded variables, the type and subtype must be provisioned. The value may be provisioned. If it is not provisioned it must be specified as part of the variable reference. In a list of segments, an embedded variable value specification applies only to the segment that directly precedes it. If a segment has multiple embedded variables, the values must be given in the order in which the variables are encountered when the segment is played. Some examples follow below: A standalone variable: S: pa(an=vb(mny,usd,1153)) Cromwell Informational [Page 18] RFC 2897 MGCP Advanced Audio Package August 2000 An embedded variable: S: pa(an=37<1153>) Not all variables, such as the date variable shown in the next example, require a subtype. In that case, the subtype is encoded with the value "null": S: pa(an=vb(dat,null,101598)) In some cases it may be desirable to play an announcement that contains an embedded variable without playing the variable itself. To do this a single "null" is provided for the value: S: pa(an=37<null>) | Variables Qualifiers | |_
Symbol Definition Type Subtype Subtype Of
_||__
dat date x
dig digits x
gen generic x dig
ndn North American DN x dig
dur duration x
mth month x
mny money x
num number x
crd cardinal x nm
ord ordinal x nm
sil silence x
str string x
txt text x
dsp display text x txt
spk text to speech x txt
tme time x
t12 twelve hour format x tme
t24 twenty four hour format x tme
ton tone x
wkd weekday x
_||__
 Date:
    Speaks a date specified as YYYYMMDD (per ISO 8601, International
    Date and Time Notation [7]).  For example "19981015" is spoken as
    "October fifteenth nineteen ninety eight".

Cromwell Informational [Page 19] RFC 2897 MGCP Advanced Audio Package August 2000

 Digits:
    Speaks a string of digits one at a time.  If the subtype is North
    American DN, the format of which is NPA-NXX-XXXX, the digits are
    spoken with appropriate pauses between the NPA and NXX and between
    the NXX and XXXX.  If the subtype is generic, the digits are
    spoken no pauses.
 Duration:
    Duration is specified in seconds and is spoken in one or more
    units of time as appropriate, e.g. "3661" is spoken as "One hour,
    one minute, and one second".
 Money:
    Money is specified in the smallest units of a given currency and
    is spoken in one or more units of currency as appropriate, e.g.
    "110" in U.S. Dollars would be spoken "one dollar and ten cents".
    The three letter codes defined in ISO 4217, Currency And Funds
    Code List [5] are used to specify the currency subtype. A small
    excerpt from ISO 4217 follows:
    __________________________________________________________
    |Alpha-code | Numeric-code | Currency |      Entity       |
    |___________|______________|__________|___________________|
    |GQE        | 226          | Ekwele   | Equatorial Guinea |
    |GRD        | 300          | Drachma  | Greece            |
    |GTQ        | 320          | Quetzal  | Guatemala         |
    |___________|______________|__________|___________________|
    Money can be specified in negative or positive units of currency.
    In the above example "-110" would be spoken as "minus one dollar
    and ten cents".
 Month:
    Speaks the specified month, e.g. "10" is spoken as "October".
    Specification is in MM format with "01" denoting January, "02"
    denoting February, etc.
 Number:
    Speaks a number in cardinal form or in ordinal form.  For example,
    "100" is spoken as "one hundred" in cardinal form and "one
    hundredth" in ordinal form.  Cardinal numbers can be specified as
    negative or positive.

Cromwell Informational [Page 20] RFC 2897 MGCP Advanced Audio Package August 2000

 Silence:
    Plays a specified period of silence.  Specification is in 100
    millisecond units.
 String:
    Speaks each character of a string, e.g. "a34bc" is spoken "A,
    three, four, b, c".  Valid characters are a-z, A-Z, 0-9, #, and *.
 Text:
    Produces the specified text as speech or displays it on a device.
 Time:
    Speaks a time in either twelve hour format or twenty four hour
    format depending on the specified subtype. For example "1700" is
    spoken as "Five pm" in twelve hour format or as "Seventeen hundred
    hours" in twenty four hour format.  Specification is in HHMM
    format per ISO 8601, International Data and Time Notation [7].
 Tone:
    Plays an algorithmically generated tone, specification of which is
    tbd. Probably most applications will use prerecorded tones.
 Weekday:
    Speaks the day of the week, e.g. "Monday".  Weekdays are specified
    as single digits, with "1" denoting Sunday, "2" denoting Monday,
    etc.

9. Selectors

 Selector types, except for the pre-defined "Lang" (language)
 selector, are definable by the user and may be applied to an
 individual segment within an operation or to all the segments in an
 operation.  For each selector type, the user must also define a range
 of values that the selector can assume.
 For example, if the user defines a selector of type "phase-of-the-
 moon", he might also define the legal values for that selector to be
 "new", "half", "full", "harvest", and "blue".  For the selector to
 actually work at runtime, audio associated with each of the selector
 values must be provisioned.

Cromwell Informational [Page 21] RFC 2897 MGCP Advanced Audio Package August 2000

 Although not required, it is suggested that the three letter codes
 defined in ISO standard 639-2, Code For The Representation Of Names
 Of Languages [4] be used as values for user defined language
 selectors.  A small excerpt from ISO 639-2 follows:
                           _________________
                           |Code | Language |
                           |_____|__________|
                           |cze  | Czech    |
                           |cym  | Welsh    |
                           |dan  | Danish   |
                           |_____|__________|
 Selectors can apply to entire operations or to a segment within an
 operation.  If an operation contains multiple segments, each segment
 may have its own set of selectors. If selectors for an individual
 segment and selectors for the entire operation are present, the
 selector for the individual segment takes precedence for that
 segment.  The selectors for the operation apply to all segments
 within that operation that do not have individual segment selectors.
 If a selector set is not specified, provisioned defaults are used.
 Selectors are applied to variables only after the variable has been
 resolved. For instance if a date variable resolved to "October 15th,
 1998" the voice with which the variable is spoken could resolve to
 either male or female if a gender selector had been defined.

10. Aliases

 Aliasing of audio segments is supported.  The alias to segment id
 mapping is provisioned and at runtime the alias is resolved to its
 associated segment id. The syntax for an alias is inclusion of the
 alias between two forward slashes, e.g.:
    S: pa(an=/not-in-service/)

11. Examples

 This section presents a number of examples of how the syntax is used.
 Note that arguments to an event are separated by a one or more
 whitespace characters, which can be either an ASCII space character
 or an ASCII tabulation character.
 Play an announcement that consists of a single segment:
    S: pa(an=39)

Cromwell Informational [Page 22] RFC 2897 MGCP Advanced Audio Package August 2000

 Play an announcement that consists of multiple segments:
    S: pa(an=39,40,47)
 Play an announcement that consists of a recording followed by silence
 followed by text to speech followed by a standalone voice variable:
    S: pa(an=39 si(30) ts(hello) vb(my,usd,3999))
 Play an announcement with an embedded variable.  If the first three
 segments of the previous announcement were provisioned as segment 40,
 the following would be exactly equivalent to the play in the
 preceding example:
    S: pa(an=40<3999>)
 Play an announcement with two embedded variables:
    S: pa(an=113<3999,10151998>)
 Play a prompt and collect a single digit.  If need be, play a
 reprompt, a no digits prompt, and a success or failure announcement.
 Give the user three attempts to enter a digit:
    S: pc(ip=21 rp=109 nd=102 fa=81 sa=72 na=3)
 Play a prompt and collect a single digit.  If the user does not enter
 a digit replay the initial prompt.  Give the user three attempts to
 enter a digit:
    S: pc(ip=21 na=3)
 Play a prompt and record voice.  If the user does not speak play a no
 speech prompt.  Give the user two attempts to record:
    S: pr(ip=22 ns=42 na=2)
 Play an announcement at ninety percent of its original speed and five
 decibels softer than its original volume.  Play the announcement
 three times with two seconds of silence between plays.
    S: pa(an=27 sp=90 vl=-5 it=3 iv=20)
 Give the user two attempts to enter a three digit pattern.  Clear the
 digit buffer before playing the prompt. The user can signal end of
 input using the # key, which is not returned to the call agent with
 the collected digits.

Cromwell Informational [Page 23] RFC 2897 MGCP Advanced Audio Package August 2000

    S: pc(ip=43 cb=true mn=3 mx=3 na=2)
 Give the user three attempts to enter a three digit pattern.  If the
 user enters one digits or two digits on the first or second attempts
 a reprompt is played.  If the user enters no digits on the first or
 second attempts a no digits reprompt is played.  If all three
 attempts fail, a failure announcement is played.  If one of the
 attempts is successful, a success announcement is played and the
 collected digits are returned to the call agent.  The user can signal
 end of input using the # key.  If the # key terminates a successful
 input attempt, the collected digits, but not the # key, are returned
 to the call agent.
    S: pc(ip=87 rp=5 nd=409 fa=9 sa=18 mx=3 na=3)
 Give the user a single attempt to enter a a 1 to 4 digit pattern,
 allow 8 seconds for the user to enter the first digit, and allow 6
 seconds for the user to enter each subsequent digit.  If the
 subsequent digit timer expires after the user has less than four
 digits, the digits collected are returned to the call agent.  The
 user can signal end of input using the # key which is not returned to
 the call agent with the collected digits.
    S: pc(ip=4 fdt=80 idt=60 mx=4)
 Give the user three chances to enter an 11 digit number that begins
 with 0 or 1.  If the user makes a mistake while entering digits, he
 can press the * key to discard any digits already collected, replay
 the prompt, and resume collection.
    S: pc(ip=33 mn=11 mx=11 sik=01 rsk=* na=3)
 Give the user three chances to enter an 11 digit number that begins
 with 0 or 1.  If the user makes a mistake while entering digits, he
 can press the key sequence *11 to discard any digits already
 collected, replay the prompt, and resume collection.  If the user
 enters the key sequence *12 the play collect is terminated along with
 any queued events, and the terminating key sequence is returned to
 the call agent for processing.
    S: pc(ip=33 mn=11 mx=11 sik=01 rsk=*11 rtk=*12 na=3)
 Give the user two chances to make a recording.  After playing the
 prompt, wait 5 seconds for the user to speak, otherwise replay the
 initial prompt and try again.  If the user does speak, wait for seven
 seconds after speech stops to make sure the user is finished.  If the
 recording is successful, return a reference to the recording to the
 call agent.

Cromwell Informational [Page 24] RFC 2897 MGCP Advanced Audio Package August 2000

    S: pr(ip=6 prt=50 pst=70 na=2)
 Play an announcement in the default language:
    S: pa(an=5)
 Play the same announcement the English.  In the first example, the
 selector applies to the an segment; in the second it applies to the
 pa operation.  For these particular examples, the net effect is the
 same.
    S: pa(an=5[Lang=eng])    or    S: pa(an=5)[Lang=eng]
 Play an announcement in Danish using a female voice with a Cajun
 accent.
    S: pa(an=6)[Lang=dan,gender=female,accent=cajun]
 Play the first part of an announcement in English, the second part in
 the default language, and the third part in French.
    S: pa(an=5[Lang=eng],6,7[Language=fra])
 Play an announcement with an embedded variable in English:
    S: pa(an=5<101599>)[Lang=eng]

12. Formal Syntax Description

AudPkgEvent = PlayAnnouncement / PlayCollect / PlayRecord /

            OperationComplete / OperationFailed / EndSignal

PlayAnnouncement = [ AdvAudioPkgToken SLASH ] PlayAnnToken

                  LPAREN PlayAnnParmList RPAREN  [ OpSelectorList ]

PlayCollect = [ AdvAudioPkgToken SLASH ] PlayColToken

              LPAREN [ PlayColParmList ]  RPAREN  [ OpSelectorList ]

PlayRecord = [ AdvAudioPkgToken SLASH ] PlayRecToken

             LPAREN [ PlayRecParmList ]  RPAREN  [ OpSelectorList ]

OperationComplete = [ AdvAudioPkgToken SLASH ] OpCompleteToken

             LPAREN OpCompleteParmList  RPAREN

OperationFailed = [ AdvAudioPkgToken SLASH ] OpFailedToken

             LPAREN ReturnCodeParm RPAREN

Cromwell Informational [Page 25] RFC 2897 MGCP Advanced Audio Package August 2000

EndSignal = [ AdvAudioPkgToken SLASH ] EndSignalToken

            LPAREN SignalParm RPAREN

OpSelectorList = LSQUARE OpSelector *( COMMA OpSelector ) RSQUARE

OpSelector = NAME EQUALS NAME

PlayAnnParmList = PlayAnnParm *( WSP PlayAnnParm )

PlayColParmList = PlayColParm *( WSP PlayColParm )

PlayRecParmList = PlayRecParm *( WSP PlayRecParm )

OpCompleteParmList = OpCompleteParm *( WSP OpCompleteParm )

PlayAnnParm = ( AnnouncementParm / IterationsParm / IntervalParm /

                DurationParm / SpeedParm / VolumeParm )

PlayColParm = ( InitPromptParm / RepromptParm / NoDigitsParm /

                FailAnnParm / SuccessAnnParm / NoInterruptParm /
                SpeedParm / VolumeParm / ClearBufferParm /
                MaxDigitsParm / MinDigitsParm / DigitPatternParm /
                FirstDigitParm / InterDigitParm / ExtraDigitParm /
                RestartKeyParm / ReinputKeyParm / ReturnKeyParm /
                PosKeyParm / StopKeyParm / StartInputKeyParm /
                EndInputKeyParm / IncludeEndInputKey /
                NumAttemptsParm  )

PlayRecParm = ( InitPromptParm / RepromptParm / NoSpeechParm /

                FailAnnParm / SuccessAnnParm / NoInterruptParm /
                SpeedParm / VolumeParm / ClearBufferParm /
                PreSpeechParm / PostSpeechParm / RecordLenParm /
                RestartKeyParm / ReinputKeyParm / ReturnKeyParm /
                PosKeyParm / StopKeyParm / EndInputKeyParm /
                RecPersistParm / OverrideAudioParm /
                RestoreAudioParm /  DeletePersistParm /
                NumAttemptsParm  )

OpCompleteParm = ( VoiceInterruptParm / IntKeySeqParm /

                   NumAttemptsParm / AmtPlayedParm / DigitsColParm /
                   RecordingIdParm / ReturnCodeParm )

AnnouncementParm = AnParmToken EQUALS Segmentlist

InitPromptParm = IpParmToken EQUALS Segmentlist

RepromptParm = RpParmToken EQUALS Segmentlist

Cromwell Informational [Page 26] RFC 2897 MGCP Advanced Audio Package August 2000

NoDigitsParm = NdParmToken EQUALS Segmentlist

NoSpeechParm = NsParmToken EQUALS Segmentlist

FailAnnParm = FaParmToken EQUALS Segmentlist

SuccessAnnParm = SaParmToken EQUALS Segmentlist

DurationParm = DuParmToken EQUALS NUMBER

IterationsParm = ItParmToken EQUALS ( NUMBER / "-1" )

IntervalParm = IvParmToken EQUALS NUMBER

SpeedParm = SpParmToken EQUALS SIGNEDINT

VolumeParm = VlParmToken EQUALS SIGNEDINT

NoInterruptParm = NiParmToken EQUALS BOOLSTR

ClearBufferParm = CbParmToken EQUALS BOOLSTR

MaxDigitsParm = MxParmToken EQUALS NUMBER

MinDigitsParm = MnParmToken EQUALS NUMBER

DigitPatternParm = DpParmToken EQUALS DIGITPATTERN

FirstDigitParm = FdtParmToken EQUALS NUMBER

InterDigitParm = IdtParmToken EQUALS NUMBER

ExtraDigitParm = EdtParmToken EQUALS NUMBER

PreSpeechParm = PrtParmToken EQUALS NUMBER

PostSpeechParm = PstParmToken EQUALS NUMBER

RecordLenParm = RltParmToken EQUALS NUMBER

RestartKeyParm = RskParmToken EQUALS CommandKeySequence

ReinputKeyParm = RikParmToken EQUALS CommandKeySequence

ReturnKeyParm = RtkParmToken EQUALS CommandKeySequence

PosKeyParm = PskParmToken EQUALS KeyPadKey COMMA PosKeyAction

Cromwell Informational [Page 27] RFC 2897 MGCP Advanced Audio Package August 2000

PosKeyAction = FirstSegmentToken / LastSegmentToken /

               PreviousSegmentToken / NextSegmentToken /
               CurrentSegmentToken

StopKeyParm = StkParmToken EQUALS KeyPadKey

StartInputKeyParm = SikParmToken EQUALS KeySet

EndInputKeyParm = EikParmToken EQUALS KeyPadKey

IncludeEndinputKey = IekParmToken EQUALS BOOLSTR

RecPersistParm = RpaParmToken EQUALS BOOLSTR

OverrideAudioParm = OaParmToken EQUALS SEGID

RestoreAudioParm = RaParmToken EQUALS SEGID

DeletePersistParm = DpaParmToken EQUALS SEGID

NumAttemptsParm = NaParmToken EQUALS NUMBER

VoiceInterruptParm = ViParmToken EQUALS BOOLSTR

IntKeySeqParm = IkParmToken EQUALS CommandKeySequence

AmtPlayedParm = ApParmToken EQUALS NUMBER

DigitsColParm = DcParmToken EQUALS KeySequence

RecordingIdParm = RiParmToken EQUALS NUMBER

ReturnCodeParm = RcParmToken EQUALS 3*3(DIGIT)

KeyPadKey = "1" / "2" / "3" / "4" / "5" / "6" / "7" / "8" / "9" /

              "*" / "#"

CommandKeySequence = 1*3(KeyPadKey)

KeySequence = 1*64(KeyPadKey)

KeySet = 1*11(KeyPadKey)

SignalParm = SgParmToken EQUALS ( PlayAnnToken / PlayColToken /

             PlayRecToken ) RPAREN

Segmentlist = SegmentDescriptor *( COMMA SegmentDescriptor )

Cromwell Informational [Page 28] RFC 2897 MGCP Advanced Audio Package August 2000

SegmentDescriptor = ( ( SegmentId [ EmbedVarList ]

                        [ SegSelectorList ]  ) /
                      ( TextToSpeechSeg [ SegSelectorList ]  ) /
                      ( DisplayTextSeg [ SegSelectorList ]  )  /
                      ( VariableSeg [ SegSelectorList ]  ) /
                        SilenceSeg )

SegmentId = ( Segid / Alias )

TextToSpeechSeg = TextToSpeechSegToken LPAREN NAME RPAREN

DisplayTextSeg = DisplayTextSegToken LPAREN NAME RPAREN

SilenceSeg = SilenceSegToken LPAREN NAME RPAREN

VariableSeg = VariableSegToken LPAREN FullSpecVar RPAREN

Segid = NUMBER

Alias = SLASH NAME SLASH

EmbedVarList = LANGLE NAME *( COMMA NAME ) RANGLE

SegSelectorList = LSQUARE SegSelector *( COMMA SegSelector ) RSQUARE

SegSelector = NAME EQUALS NAME

FullSpecVar = ( DateVariable / DigitsVariable / DurationVariable /

                MonthVariable / MoneyVariable / NumberVariable /
                SilenceVariable / StringVariable / TextVariable /
                TimeVariable / WeekdayVariable )

DateVariable = DateVarToken COMMA NullStrToken COMMA Date

Date = 8*8(DIGIT)

DigitsVariable = DigitsVarToken COMMA (NorthAmericanDnToken /

                 GenericDigitsToken) COMMA NUMBER

DurationVariable = DurationVarToken COMMA NullStrToken COMMA NUMBER

MoneyVariable = MoneyVarToken COMMA 3*3(ALPHA) COMMA OPTSIGNEDINT

MonthVariable = MonthVarToken COMMA NullStrToken COMMA Month

Month = "01" / "02" / "03" / "04" / "05" / "06" / "07" / "08" / "09" /

      "10" / "11" / "12"

Cromwell Informational [Page 29] RFC 2897 MGCP Advanced Audio Package August 2000

NumberVariable = (NumberVarToken COMMA CardinalNumberToken COMMA

                  OPTSIGNEDINT) / (NumberVarToken COMMA
                  OrdinalNumberToken COMMA NUMBER)

SilenceVariable = SilenceVarToken COMMA NullStrToken COMMA NUMBER

StringVariable = StringVarToken COMMA NullStrToken COMMA *(KeyPadKey)

                 OrdinalNumberToken) COMMA NUMBER

SilenceVariable = SilenceVarToken COMMA NullStrToken COMMA NUMBER

StringVariable = StringVarToken COMMA NullStrToken COMMA

  • (KeyPadKey)

TextVariable = TextVarToken COMMA (DisplayTextToken /

               TextToSpeechToken) COMMA NAME

TimeVariable = TimeVarToken COMMA (TwelveHourFormatToken /

               TwentyFourHourFormatToken) COMMA 4*4(DIGIT)

WeekdayVariable = WeekdayVarToken COMMA NullStrToken COMMA NAME

AdvAudioPkgToken = "A" PlayAnnToken = "pa" PlayColToken = "pc" PlayRecToken = "pr" OpCompleteToken = "oc" OpFailedToken = "of" EndSignalToken = "es" TextToSpeechSegToken = "ts" DisplayTextSegToken = "dt" SilenceSegToken = "si" VariableSegToken = "vb" AnParmToken = "an" IpParmToken = "ip" RpParmToken = "rp" NdParmToken = "nd" NsParmToken = "ns" FaParmToken = "fa" SaParmToken = "sa" NiParmToken = "ni" ItParmToken = "it" IvParmToken = "iv" DuParmToken = "du" SpParmToken = "sp" VlParmToken = "vl" CbParmToken = "cb" MxParmToken = "mx"

Cromwell Informational [Page 30] RFC 2897 MGCP Advanced Audio Package August 2000

MnParmToken = "mn" DpParmToken = "dp" FdtParmToken = "fdt" IdtParmToken = "idt" EdtParmToken = "edt" PrtParmToken = "prt" PstParmToken = "pst" RltParmToken = "rlt" RskParmToken = "rsk" RikParmToken = "rik" RtkParmToken = "rtk" PskParmToken = "psk" StkParmToken = "stk" SikParmToken = "sik" EikParmToken = "eik" IekParmToken = "iek" RpaParmToken = "rpa" DpaParmToken = "dpa" OaParmToken = "oa" RaParmToken = "ra" NaParmToken = "na" RidParmToken = "rid" ViParmToken = "vi" IkParmToken = "ik" ApParmToken = "ap" DcParmToken = "dc" RiParmToken = "ri" RcParmToken = "rc" SgParmToken = "sg" DateVarToken = "dat" DigitsVarToken = "dig" DuratioNVarToken = "dur" MoneyVarToken = "mny" MonthVarToken = "mth" NumberVarToken = "num" SilenceVarToken = "sil" StringVarToken = "str" TextVarToken = "txt" TimeVarToken = "tme" WeekdayVarToken = "wkd" GenericDigitsToken = "gen" NorthAmericanDnSToken = "ndn" CardinalNumberToken = "crd" OrdinalNumberToken = "ord" DisplayTextToken = "dsp" TextToSpeechToken = "spk" TwelveHourFormatToken = "t12" TwentyFourHourFormatToken = "t24"

Cromwell Informational [Page 31] RFC 2897 MGCP Advanced Audio Package August 2000

NullStrToken = "null" FirstSegmentToken = "fst" LastSegmentToken = "lst" PreviousSegmentToken = "prv" NextSegmentToken = "nxt" CurrentSegmentToken = "cur" BOOLSTR = "true" / "false" NAMECHAR = ALPHA / DIGIT / "_" / "-" NAME = 1*64(NAMECHAR) NUMBER = DIGIT *31(DIGIT) SIGNEDINT = ("+" / "-") DIGIT *31(DIGIT) OPTSIGNEDINT = ["+" / "-"] DIGIT *31(DIGIT) EQUALS = "=" COMMA = "," LSQUARE = "[" RSQUARE = "]" LANGLE = "<" RANGLE = ">" LPAREN = "(" RPAREN = ")" SLASH = "/" WSP = SP / HTAB

13. References

 [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
     Levels", BCP 14, RFC 2119, March 1997.
 [2] Arango, M., Dugan, A., Elliott, I., Huitema, C. and S. Pickett,
     "Media Gateway Control Protocol (MGCP) Version 0.1", RFC 2705,
     October 1999.
 [3] Cromwell, D. and M. Durling, "Requirements For Control Of A Media
     Services Function", Version 0.0, Work in Progres..
 [4] ISO 639-2, "Code For The Representation Of Names Of Languages",
     1998.
 [5] ISO 4217, "Currency And Funds Code List", 1981.
 [6] Cuervo, F., Hill, B., Greene, N., Huitema, C., Rayhan, A., Rosen,
     B. and J. Segers, "Megaco Protocol", RFC 2885, August 2000.
 [7] ISO 8601, "International Date and Time Notation", 1998.

Cromwell Informational [Page 32] RFC 2897 MGCP Advanced Audio Package August 2000

14. Author's Address

 David Cromwell
 Nortel Networks
 Box 13478
 35 Davis Drive
 Research Triangle Park, NC 27709
 Phone: 919-991-8870
 EMail: cromwell@nortelnetworks.com

Cromwell Informational [Page 33] RFC 2897 MGCP Advanced Audio Package August 2000

15. Full Copyright Statement

 Copyright (C) The Internet Society (2000).  All Rights Reserved.
 This document and translations of it may be copied and furnished to
 others, and derivative works that comment on or otherwise explain it
 or assist in its implementation may be prepared, copied, published
 and distributed, in whole or in part, without restriction of any
 kind, provided that the above copyright notice and this paragraph are
 included on all such copies and derivative works.  However, this
 document itself may not be modified in any way, such as by removing
 the copyright notice or references to the Internet Society or other
 Internet organizations, except as needed for the purpose of
 developing Internet standards in which case the procedures for
 copyrights defined in the Internet Standards process must be
 followed, or as required to translate it into languages other than
 English.
 The limited permissions granted above are perpetual and will not be
 revoked by the Internet Society or its successors or assigns.
 This document and the information contained herein is provided on an
 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

 Funding for the RFC Editor function is currently provided by the
 Internet Society.

Cromwell Informational [Page 34]

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