Sentinel Express 4.1 :: Sentinel Administration Guide :: SIP Subscriber Determination Feature

This feature inspects the initial SIP request to determine the subscriber address and subscription ID for the current session.

Description

Feature name	SipSubscriberDetermination
Applicable contexts	SIP service
SAS Support	Yes
Prerequisite features	DetermineCallType

Feature name

SipSubscriberDetermination

Applicable contexts

SIP service

SAS Support

Yes

Prerequisite features

DetermineCallType

Leg Manager inputs

Leg	Name	Type	Purpose
calledParty	MessagesToSend	SipMessageQueue	Retrieve the outbound SIP request on the called party leg.

Leg

Name

Type

Purpose

calledParty

MessagesToSend

SipMessageQueue

Retrieve the outbound SIP request on the called party leg.

Session state inputs and outputs

Inputs

Name	Type	Purpose
CallType	CallType enum	Determines which header to inspect for the subscriber address if P-Served-User is not present.
Subscriber	String	Checked to ensure the feature does not overwrite an already determined subscriber address.
SubscriptionId	String	Checked to ensure the feature does not overwrite an already determined subscription ID.

Name

Type

Purpose

CallType

CallType enum

Determines which header to inspect for the subscriber address if P-Served-User is not present.

Subscriber

String

Checked to ensure the feature does not overwrite an already determined subscriber address.

SubscriptionId

String

Checked to ensure the feature does not overwrite an already determined subscription ID.

Outputs

Name Type Purpose

Name	Type	Purpose
Subscriber	String	Set to the determined subscriber address, if it was not already set.
SubscriptionId	String	Set to the determined subscription ID, if it was not already set.
SubscriptionIdType	SubscriptionIdType enum	Set to the type of the determined subscription ID. `END_USER_E164` if the subscriber address contains a valid phone number, otherwise `END_USER_SIP_URI`.

Subscriber

String

Set to the determined subscriber address, if it was not already set.

SubscriptionId

String

Set to the determined subscription ID, if it was not already set.

SubscriptionIdType

SubscriptionIdType enum

Set to the type of the determined subscription ID. END_USER_E164 if the subscriber address contains a valid phone number, otherwise END_USER_SIP_URI.

Error scenarios

Scenario	Handling
Calling or Called party leg not found.	Report featureFailedToExecute
No outbound request on called party leg.	Report featureFailedToExecute
Failure to parse SIP headers	Report featureFailedToExecute
No Call Type in session state	Report featureFailedToExecute
No subscriber address could be determined from any of the expected headers	Report featureFailedToExecute

Scenario

Handling

Calling or Called party leg not found.

Report featureFailedToExecute

No outbound request on called party leg.

Report featureFailedToExecute

Failure to parse SIP headers

Report featureFailedToExecute

No Call Type in session state

Report featureFailedToExecute

No subscriber address could be determined from any of the expected headers

Report featureFailedToExecute

Feature responses

Response	Reason
featureFailedToExecute	Any of the error scenarios described above/
featureHasFinished	Feature completed execution, regardless of whether a subscriber address was successfully determined or not.

Response

Reason

featureFailedToExecute

Any of the error scenarios described above/

featureHasFinished

Feature completed execution, regardless of whether a subscriber address was successfully determined or not.

Configuration

This feature has no configuration.

Behaviour

The feature examines the outbound SIP request towards the called party to determine the subscriber address and subscription ID for the session. Examining the outbound request ensures the feature sees any modifications made by earlier features in the call flow (e.g. Normalisation).

The feature determine two pieces of information: the subscriber address and the subscription ID.

Subscriber address

The subscriber address is determined through the following steps:

Check if the Subscriber session state field is already set. If so, use that value as the subscriber address.
Check if the outbound SIP request contains a P-Served-User header. If so, use the URI in that header as the subscriber address.
Check the Call Type in session state.
- For MobileOriginating, MobileForwarded, and NetworkInitiated call types, check if the outbound SIP request contains a P-Asserted-Identity header. If so, use the URI in that header as the subscriber address.
- For MobileTerminating call types, use the Request-URI as the subscriber address.

If after these steps a subscriber address has been determined, any URI parameters will be removed and the resulting value set in the Subscriber session state field.

If no subscriber address could be determined, the feature reports and error and finishes execution.

Subscription ID

The subscription ID is derived from the source as the subscriber address determined in the previous steps.

There are two parts to the subscription ID:

the subscription ID value, to be set in the SubscriptionId session state field, and
the subscription ID type, to be set in the SubscriptionIdType session state field.

If the SubscriptionId session state field is already set, the feature will not modify the subscription ID value or type.

If it is not set, the feature will attempt to determine the subscription ID value and type as follows:

If the data source for the subscriber address is:

A tel: URI, or
A sip: URI with the user part being a valid local or global phone number according to RFC 2806, and the user=phone parameter set

then the number will be extracted from the URI and set in the SubscriptionId session state field. The SubscriptionIdType field will be set to END_USER_E164.

Otherwise, the URI will be stripped of any parameters and set in the SubscriptionId session state field. The SubscriptionIdType field will be set to END_USER_SIP_URI.

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