SIP Header tags

Voice applications can use SIP tags to send and receive information including Universal Resource Indicators (URIs) to and from the SIP stack. Information on how to use each SIP tag supported by Blueworx Voice Response is provided here.

The tags take the form tag name: value. For example:

TO_HDR= sip: user@uk.ibm.com
FROM_HDR= sip: wvr@uk.ibm.com

The value of the tag is always defined as a string and must follow the SIP standard for the header type that is used.

The tags can be used with MakeCall, AnswerCall, TransferCall, and TerminateCall state table actions. For more information on state table actions and system variables, see Blueworx Voice Response for AIX: Application Development using State Tables.

The system variables that are used are:

To ensure that these three System Variables contain the correct information, the Call Information Type parameter must be set to Signalling Process in the System Configuration GUI. See Call Information Type for more information.

SIP tag information contained in SV542 is also accessible from VoiceXML applications. For more information, see Using Blueworx Voice Response call tags.

SIP tag information contained in SV541 and SV542 is also accessible from CCXML applications. For more information, see Using Blueworx Voice Response call tags.

The following sections describe each SIP tag supported by Blueworx Voice Response and how to use it with the product:

TO_HDR

A SIP 'To Header' tag. This is the address to which the request is sent. This corresponds to the called number in a traditional telephony system. The standard character format for a SIP URI is UTF-8.

Size
The maximum length of the tag is 256 characters.
Valid attributes
None.
Valid usage
  • In a SIP INVITE message on an inbound call in SV542.
  • In an INVITE message on an outbound MakeCall action in SV541.
  • In a REFER message on a TransferCall action in SV541 for a blind transfer.
  • In an INVITE message on a TransferCall action in SV541 for an attended transfer.
Examples

When using a proxy:

sip:john@mydomain.com

When not using a proxy:

sip:john@mycomputer.mydomain.com:5060 (the port is optional, the default is 5060).

FROM_HDR

A SIP 'From Header' tag. This is the address from which the request is sent. This relates to the calling number in a traditional telephony system. The standard character format for a SIP URI is UTF-8.

Size
The maximum length of the tag is 256 characters.
Valid attributes
None.
Valid usage
  • In a SIP INVITE message on an inbound call in SV542.
  • In an INVITE message on an outbound MakeCall action in SV541.
  • In a REFER message on a TransferCall action in SV541 for a blind transfer.
  • In an INVITE message on a TransferCall action in SV541 for an attended transfer.
Example
"harry" <sip:tom@mycomputer.mydomain.com>;
PASSID_HDR

A SIP 'P-Asserted-Identity' tag. Added by a SIP proxy when the SIP calling ID (in the From header) has been authenticated. For more information on the usage of 'P-Asserted-Identity', refer to SIP RFC3325.

Size
The maximum length of the tag is 256 characters.
Valid attributes
None
Valid usage
  • In an INVITE message on an outbound MakeCall action in SV541.
  • In an INVITE message on a TransferCall action in SV541 for an attended transfer.
Example
P-Asserted-Identity: "fred"<sip:123456@anyhost.com>

In this example, 123456 would be extracted as the calling number passed in SV186, and everything following P-Asserted-Identity: would be passed in tagged string SV542.

PRIVACY_HDR

A SIP 'Privacy' tag. Indicates whether presentation of the calling id (in the P-Asserted-Identity) header is to be suppressed or allowed.

Size
The maximum length of the tag is 256 characters.
Valid attributes
None.
Valid usage
  • In a SIP INVITE message on an inbound call in SV542.
  • In an INVITE message on an outbound MakeCall action in SV541.
  • In an INVITE message on a TransferCall action in SV541 for an attended transfer.
Example
Privacy: none
REQ_HDR

A SIP 'Request Header' tag. This is an actual address and defines the 'first hop' for an outbound request. This may be a proxy server or gateway which will then forward the request to the address defined in the TO_HDR. If a REQ_HDR tag is present it will override any routing information that has been configured on the system. The standard character format for a SIP URI is UTF-8.

Size
The maximum length of the tag is 256 characters.
Valid attributes
None.
Valid usage
  • In a SIP INVITE message on an inbound call in SV542.
  • In an INVITE message on an outbound MakeCall action in SV541.
Example
sip:john@99.23.45.7
RPARTYID_HDR

A SIP 'Remote-Party-ID' tag. Support provided for compatibility with existing gateways.

To determine Calling number (passed in SV186), Blueworx Voice Response looks for headers in the following order of priority:

  1. P-Asserted-Identity
  2. Remote-Party-ID
  3. From
Note: Remote-Party-ID is included for compatibility with older SIP equipment and is now superseded by 'P-Asserted-Identity' and Privacy. SIP RFCs 3323 and 3325 refer.
Size
The maximum length of the tag is 256 characters.
Valid attributes
None.
Valid usage
  • In an INVITE message on an outbound MakeCall action in SV541.
  • In an INVITE message on a TransferCall action in SV541 for an attended transfer.
Example
Remote-Party-ID: "Bob"<sip:123456@anyhost.com>;party=calling;privacy=none
SUBJECT_HDR

A SIP 'Subject Header'. This is used to send information on the TerminateCall state table action. This may be information required to complete the call (to connect the user to a directory lookup number), and can be used as an alternative to call transfer (REFER). The standard character format for a SIP URI is UTF-8.

Size
The maximum length of the tag is 256 characters.
Valid attributes
None.
Valid usage
  • In a SIP INVITE message on an inbound call in SV542.
  • In a BYE message on a TerminateCall action in SV541.
Example
"1,5551234,555678"
DIV_HDR

A SIP 'Diversion Header'. The diversion header tag can contain a URI and certain attributes that describe the parameters that may be received with it (for example, the reason for the diversion). The standard character format for a SIP URI is UTF-8. A SIP message can contain multiple diversion headers. Blueworx Voice Response extracts the first of these (top) into the DIV_HDR string, but also uses the first to extract the Original Called Number into SV187 and the last (bottom) to extract the Last Redirecting Number into SV188.

Size
The maximum length of the tag is 256 characters.
Valid usage
  • In a SIP INVITE message on an inbound call in SV542.
  • In an INVITE message on an outbound MakeCall action in SV541.
  • In an INVITE message on a TransferCall action in SV541 for an attended transfer.
Example
sip:john@hursley.ibm.com:5060;reason='do-not-disturb'

The reason code is added as an attribute.

DIVERT attributes
DIV_HDR.reason

A SIP 'Diversion Header' tag attribute.

Size
The maximum length of the tag is 20 characters.
Examples of the diversion reason attribute

"unknown"

"user-busy"

"no-answer"

"unavailable"

"unconditional"

"time-of-day"

"do-not-disturb"

"deflection"

"follow-me"

"out-of-source"

"away"

DIV_HDR.counter

A SIP 'Diversion Header' tag attribute. The standard character format for a SIP URI is UTF-8.

Size
The maximum length of the tag is 2 digit characters.
Example of diversion counter attribute

"15"

DIV_HDR.limit

A SIP 'Diversion Header' tag attribute. The standard character format for a SIP URI is UTF-8.

Size
The maximum length of the tag is 2 digit characters.
Example of diversion limit attribute

"20"

DIV_HDR.privacy

A SIP 'Diversion Header' tag attribute. The standard character format for a SIP URI is UTF-8.

Size
The maximum length of the tag is 20 characters.
Examples of diversion privacy attribute

"privacy=full"

"privacy=name"

"privacy=screen"

DIV_HDR.screen

A SIP 'Diversion Header' tag attribute. The standard character format for a SIP URI is UTF-8.

Size
The maximum length of the tag is 20 characters.
Examples of diversion screen attribute

"screen=yes"

"screen=no"

DIV_HDR.ext

A SIP 'Diversion Header' tag attribute. The standard character format for a SIP URI is UTF-8.

Size
The maximum length of the tag is 20 characters.
Example of diversion extension attribute

"quoted_string"

A_LANG_HDR

A SIP 'Accept Language Header' tag. This is used in requests to indicate the preferred language or languages to be used for reason phrases, session descriptions, or status responses included in the response. If not present, all languages should be acceptable.

Size
The maximum length of the tag is 256 characters.
Valid attributes
None.
Valid usage
  • In a SIP INVITE message on an inbound call in SV542.
  • In an INVITE message on an outbound MakeCall action in SV541.
  • In an INVITE message on a TransferCall action in SV541 for an attended transfer.
Examples

da

en-gb;q=0.8

en;q=0.7

CALLID_HDR

A SIP 'Call-ID' tag. This is a unique identifier used to group together a series of messages.

Size
The maximum length of the tag is 256 characters.
Valid attributes
None.
Valid usage
  • In a SIP INVITE message on an inbound call in SV542.
Example

f81d4fae-7dec-11d0-a765-00a0c91e6bf6@myco.com

CALLINFO_HDR

A SIP 'Call-Info' tag. This provides additional information about the caller.

Size
The maximum length of the tag is 256 characters.
Valid attributes
purpose - the purpose of the URI.

card - a business card, for example, in vCard or LDIF format

icon - designates a digital image of the caller.

Valid usage
  • In a SIP INVITE message on an inbound call in SV542.
Examples

<http://wwww.example.com/alice/photo.jpg>;purpose=icon

<http://www.example.com/alice/>;purpose=info