Generic Name Interworking between SIP and SS7 - IMG

Overview:

This topic explains the interworking of the Generic Name parameter on the SS7 side with the Remote Party ID, From, and P-Asserted Identity headers on the SIP side.

 

Definitions/Acronyms:

RP-ID - The Remote-Party-ID header identifies the calling party and carries presentation and screening information

APRI - The Address Presentation Restriction Indicator are two bits that are part of the Generic Name Parameter and the Calling Party Number Parameter. The value of these bits will define whether the Generic Name Parameter is passed publicly in interworking to the From, RP-id, and P-Asserted-Identity headers.

P-Asserted-Identity - The P-Asserted-Identity header field is used in a trusted network among trusted SIP entities to carry the identity of a user sending a SIP message after being verified by authentication on a proxy server.

 

SS7 to SIP RP-id:

When interworking the Generic Name Parameter of the incoming ISUP IAM to the RP-id header 'display name' and 'privacy' tag of the SIP INVITE message, the 'privacy' tag content is determined through a combination of the APRI values of the Called Party Number and the Generic Name Parameters

 

Below is table which explains the SS7 to SIP scenario.

APRI in the Generic Name Parameter

APRI in the Calling Party Number

Privacy tag

Presentation Allowed

Presentation Allowed

Privacy = Off

Presentation Restricted

Presentation Allowed

Privacy = Name

Presentation Allowed

Presentation Restricted

Privacy = URI

Presentation Restricted

Presentation Restricted

Privacy = Full

 

Table Examples:

Example 1:

If the Generic Name Parameter is present and the value of the APRI for the Generic Name Parameter and the Calling Party Number Parameter both indicate Presentation allowed then the Privacy field of the RPID header will indicate Off. See RPID below.

 

Remote-Party-ID: “JohnSmith”<sip:1234567890@10.129.43.26;user=phone>;party=calling;id-type=subscriber;privacy=Off;screen=no

 

Example 2:

If the Generic Name Parameter is present, the APRI for the Generic Name Parameter is restricted, and the APRI for the Calling Party Number Parameter is restricted then the privacy field of the RPID will indicate full. See RPID below

 

Remote-Party-ID: "JohnSmith"<sip:1234567890@10.129.43.26;user=phone>;party=calling;id-type=subscriber;privacy=full;screen=no

 

SIP RP-id to SS7

When interworking the incoming SIP INVITE RP-id header 'display name' and 'Privacy' tag to the ISUP IAM Generic Name parameter, the APRI values of the Generic Name and the Called Party Number are determined from the RP-id header 'Privacy' tag content.

 

Note: the RP-id header will only be mapped to the IAM when party tag has a value of 'party=calling'

 

Privacy tag

APRI in the Calling Party Number

APRI in the Generic Name Parameter

Privacy=Full

Restricted

Restricted

Privacy=Off

Allowed

Allowed

Privacy=URI

Restricted

Allowed

Privacy=Name

Allowed

Restricted

 

Informative Details

  1. In the case in which the APRI of the Calling Party Number is set to “restricted”, the From header URI will be as follows:

    From: anonymous<sip:anonymous@anonymous.invalid>
     

  2. In the case in which the APRI of the Calling Party Number is set to “allowed”, the From header URI will be as follows:

    From: "Dialogic"<sip:4444@10.129.44.22>
     

  3. There are some instances that the remote SS7 carrier will not want the Generic Name Parameter sent to them in the IAM. In this case the Generic Name can be stripped from the IAM message by configuring the SS7 Parameter Filter to strip the Generic Name from the IAM. See SS7 Parameter Filter link

  4. The Remote Party ID will be interworked only if the parameter "party" is set to "calling".

  5. If the parameter "privacy" is not included in the RPID both the Calling Party Number and Generic Name will be allowed

  6. The Generic Name will be restricted to 15 characters in the Remote Party ID Display portion

 

Table Examples:

Example 1:

An incoming SIP INVITE has an RP-id header with a display name and a 'privacy' tag value, in this example, of 'name'. In this case the APRI value of the Called Party Number will be set to 'Allowed' while the APRI value of the Generic Name will be set to 'Restricted'

 

Example 2:

An incoming SIP INVITE has an RP-id header with a display name and a 'privacy' tag value, in this example, of 'off'. In this case the APRI value of both the Called Party Number and the Generic Name will be set to 'Allowed.

 

Mapping the Screen Parameter to IAM

The SIP RP-id header screen tag is interworked to the Calling Party Number 'screen indication' parameter and vice-versa as indicated in table below

 

Parameter "screen" value

Screening Indicator of Calling Party Number

screen = yes

SI = Network Provided

screen = no

SI = User Provided / Not Screened

parameter "screen" not present or invalid value

SI = User Provided / Not Screened

 

 

Mapping of SIP P-Asserted-Identity Header and Privacy Headers into IAM message

In a trusted network when interworking the incoming SIP INVITE P-Asserted-id and associated 'Privacy' headers to the ISUP IAM Generic Name parameter, the APRI values of the Called Party Number and Generic Name are determined from content or presence of the 'privacy' header.

 

Privacy Header Value

APRI in the Calling Party Number

APRI in the Generic Name Parameter

id

Restricted

Restricted

header

Restricted

Restricted

user

Restricted

Restricted

none

Allowed

Allowed

Invalid or Not Present

Allowed

Allowed

 

 

Mapping of IAM to the SIP P-Asserted-Identity Header and Privacy Headers

When interworking the Generic name optional parameter of the incoming ISUP IAM to the SIP INVITE P-Asserted-id and 'Privacy' headers, the 'Privacy' header content or presence is determined from the APRI value of the Called Party Number.

The Privacy Header is contingent only on the calling party number APRI.

 

APRI in the Calling Party Number

Privacy Header Value

Restricted

id

Allowed

none

 

 

Informative Details:

  1. The Privacy Header carries the APRI of the Calling Party Number and the mapping is shown above

  2. The P-Asserted Identity Header display-name portion is mapped into the Generic Name field

  3. The P-Asserted Identity Header user name portion (if digits) is mapped to the address digits of the Calling Party Number

  4. A maximum of 15 characters from the P-Asserted Identity Header will be placed into the Generic Name field.

  5. If there is both a Remote Party ID header and a P-Asserted Identity Header in the INVITE message the P-Asserted Identity Header Values will take precedence.

  6. To configure Privacy and P-Asserted Identity Headers see the Configuring SIP Privacy links

 

Mapping the Screen Parameter to IAM

The parameter "screen" is also interworked into the Calling Party Number. See table below:

 

Parameter "screen" value

Screening Indicator of Calling Party Number

screen = yes

SI = Network Provided

screen = no

SI = User Provided / Not Screened

parameter "screen" not present or invalid value

SI = User Provided / Not Screened

 

 

Related Topics:

SIP Privacy

SIP Signaling

SIP Headers