RU2434364C2 - System and method for indicating circuit switched access at ims registration - Google Patents

Abstract

FIELD: information technology.

SUBSTANCE: in IP multimedia subsystem (IMS), IMS control channel protocol (ICCP) is used between user equipment (UE) and IMS control channel function (ICCF) and session initiated protocol (SIP) interface (between ICCF, call session control function and application server) to support the indication of circuit switched (CS) access using P-Access-Network-Information header. The indication can be used by a serving call session control function (S-CSCF) or application server (AS) for different purposes such as routing decision, charging, and presence.

EFFECT: providing IMS with information whether a user is registered during channel switched access or packet switched access.

14 cl, 20 dwg

Description

FIELD OF THE INVENTION

The invention relates to IP Multimedia Subsystem (IMS). More specifically and not by way of limitation, the present invention is directed to a system and method for simplifying the process of registering users in IMS.

State of the art

The following is a list of abbreviations used in the description, as well as their definitions, which should be applied throughout the description, unless otherwise indicated.

Abbreviations

3GPP - Third Generation Partnership Project

ADS - access domain selection

AS - application server

CAMEL - a user application for advanced mobile logic

CDR - call data recording

CS - circuit switching

CSCF - Call Session Management Function

CSI - a combination of CS and IMS services

IA - IMS adapter

ICCF - IMS Channel Switching Function

ICCP - IMS Channel Switching Protocol

ICS - Centralized IMS Services

IMPI - Confidential Identity for IP Multimedia Subsystem

IMS - IP Multimedia Subsystem

IMSI - International Mobile Subscriber Identity

IP-CAN - access network with IP connection

ISC - IP Multimedia Subsystem Management

ISUP - ISDN subscriber subsystem

MAP - a subsystem of mobile applications

MGCF - Network Gateway Management Function

PS - packet switched

P-CSCF - Call Session Proxy

S-CSCF - Call Session Management Feature

SIP - Session Initiation Protocol

TAS - telephone application server

UE - user equipment

URL - Uniform Resource Locator

USSD - unstructured data on additional services

VCC - Voice Call Continuity

WCDMA - Code Division Broadband Multiple Access

FIG. 1 illustrates a high level block diagram of an ICS architecture 100. Centralized IMS Services (ICS) are a proposed work item in Third Generation Partnership Project (3GPP) to enable IMS services in a variety of types of access networks, such as channel switching network (CS) 102. The service implementation is hosted in IMS 110, and the CS network 102 is used as access to services in IMS 110.

Compared to 3GPP Version 7, Voice Call Continuity Architecture (VCC), CS IMS Management Function (ICCF) 106 is introduced to enable signaling not supported by CS signaling (e.g. ISUP), such as IMS registration , signaling during a call, additional information for signaling when a call is established (for example, a SIP URL) to emulate an IMS terminal in the IMS direction. Unstructured supplementary service data (USSD) can be used to transport this supplemental signaling, called ICCP (IMS CS Management) 104, to a CS network.

In VCC according to 3GPP Version 7, the VCC user is not registered in IMS with CS access, and the telephone application server (TAS) 108 must implement additional mechanisms in order to provide IMS services to the user. As a possible solution, in 3GPP Version 8, it is proposed to support IMS registration from UE 101 using ICCP so that TAS 108 can be informed from the S-CSCF through a third-party registration procedure that the user is registered in IMS. Serving CSCF is a call session management function for managing user equipment registration and routing in the IP multimedia subsystem. Another CSCF, the proxy CSCF, is the first point of contact for user equipment and manages security, verification and policy solutions. Currently, there is no procedure that informs the IMS whether the user is logged in with CS access or PS access (this is because there was no IMS registration for CS access before). The IMS can only know that the user is registered in one or more radio accesses, it being assumed that all accesses are packet accesses. Packet access (PS) has always been assumed in IMS.

Due to the assumption that access is always PS access, there are situations that cannot be resolved through a third-party IMS registration mechanism up to 3GPP Version 7. For example, an operator may want to implement a local policy when choosing an S-CSCF contact address to promote CS -Access, not PS-access; or vice versa. The operator may want to distinguish between CS and PS access charges and indicate this difference in the IMS CDR. In addition, the operator may want to distinguish between the TAS mode of operation depending on whether the user is registered with CS access or PS access (for example, a video-in-video mailbox with call forwarding if the user is registered in CS -Access where the video cannot be supported).

It would be useful to have a system and method for identifying whether a user is registered with CS or PS access, which overcome the disadvantages of the prior art. The present invention provides such a system and method.

Disclosure of invention

The present invention provides a change in the SIP interface, for example, for ICCF, CSCF, and AS, to support the CS access indicator in the P-Access-Network-Information header. The affected nodes are ICCF, S-CSCF, and AS. The indicator may be used by the S-CSCF or AS for various purposes, such as routing, billing, and presence decision information.

Thus, in one aspect, the present invention is directed to a method for registering a user equipment (UE) in an IP multimedia subsystem (IMS) by sending a registration request to a serving call session management function (S-CSCF), wherein the registration request includes a header containing information about the user's access type and contacts associated with the access type. The registration request is forwarded to the associated IMS application server, which responds to the ICCF. The S-CSCF uses the inserted registration request header to implement access rules according to the settings of the operator or user, and the header included in the registration request is the P-Access-Network-Information header, which includes contacts associated with circuit switched access.

The contact addresses associated with the circuit switched access in the header are placed in the order of use before the normal packet switched access contact, and the ordering rules regarding contact processing associated with the access type are based on the local policy in the S-CSCF. The local policy in the S-CSCF may depend on the time of day or subscriber profile.

In another aspect, the present invention is directed to a system for registering user equipment (UE) in an IP multimedia subsystem (IMS), the system comprising means for sending a registration request to a serving call session management function (S-CSCF), and a registration request includes a header containing user access type information and contacts associated with the access type. The system includes means for sending the registration request to the associated IMS application server and means for sending the registration response to the ICCF.

Tools included in the S-CSCF are provided for using the registration request header to implement access rules according to the settings of the operator or user, and the header that is included in the registration request is the P-Access-Network-Information header, which includes Contacts related to circuit switched access.

The contacts associated with the circuit switched access in the header can be placed in order before the normal packet switched access contact, and the ordering rules regarding the processing of contacts related to the type of access are based on the local policy in S-CSCF, and the local policy in S-CSCF depends on the time of day or subscriber profile.

Brief Description of the Drawings

In the following section, the invention is described with reference to exemplary embodiments illustrated in the drawings, in which:

FIG. 1 illustrates a high-level block diagram of an ICS architecture;

FIG. 2 illustrates a high level circuit switched access signal sequence during registration in accordance with an embodiment of the present invention; and

FIG. 3a, 3b, and 3c illustrate three situations in which a registered device is identified in an S-CSCF according to embodiments of the present invention;

FIG. 4a-4d illustrate situations in which ordering in an S-CSCF is changed in accordance with an embodiment of the present invention;

FIG. 5a-5d illustrate situations in which various branching actions can be taken according to an embodiment of the present invention;

FIG. 6a-6f illustrate situations regarding various sequential call actions according to an embodiment of the present invention; and

FIG. 7 illustrates a circuit switched access indication to a presence server according to an embodiment of the present invention.

The implementation of the invention

In the following description, many specific details are set forth in order to provide a thorough understanding of the invention. However, those skilled in the art should understand that the present invention can be practiced without these specific details. In other instances, well-known methods, procedures, and components are not described in detail so as not to obscure the understanding of the present invention.

The parameter associated with the IMS, "P-Access-Network-Information", is already present in order to deliver access-related network information, but additional information indicating the type of access (CS and PS) is not currently included in this parameter. Before ICS, PS access was the default case. The P-Access-Network-Information header is described below for reference:

FIG. 2 illustrates a high level circuit switched access signal sequence during registration in accordance with an embodiment of the present invention. The P-Access-Network-Information header is expanded in the present invention to indicate the type of access as CS, and is inserted by the ICCF into the ICCP for the registration request and delivered to the S-CSCF and the application server (AS). The application server may be a telephone application server or a voice call continuity AS or any other AS (for example, a presence server) that uses the registration state to run its application “on top” of the IP Multimedia Subsystem Management Interface (ISC). The S-CSCF can also use the P-Access-Network-Information to implement the rules according to the settings of the operator or user, to place the contacts associated with the CS-access in an order different from the PS-access.

FIG. 3a, 3b, and 3c illustrate three situations in which a registered device is identified in an S-CSCF according to embodiments of the present invention. The distinction between CS and PS-enabled UEs is made using the information included in the registration message provided by ICCF via ICCP. FIG. 3a illustrates the use of a “Device ID” from a UE during registration in both CS and PS. This is a new parameter in the ICCP registration request and in the SIP REGISTER message, and the S-CSCF should store the Device ID information with the IP address of the contact. For example, if two devices are registered, one of which is a UE with CS and PS access, and the other is a UE that is a PC with only PS access, the information stored in the S-CSCF is as follows:

Public User ID --- Contact IP1 --- CS access --- Device ID1

+ - Contact IP2 --- PS access --- Device ID1

+ - Contact IP3 --- PS access --- Device ID2

Note 1 to entry: IP1 is the IP address of the ICCF in the case of CS access.

FIG. 3b illustrates the inclusion of at least one “alternative contact” from the UE during CS registration. In the ICCP registration request and in the REGISTER message, the S-CSCF shall store the alternative contact information with the contact IP address for CS access. The S-CSCF can identify that two registrations belong to the same matching contact address of the device and an alternative contact address. For example, if two devices are registered, one of which is a UE with CS and PS access, and the other is a UE that is a PC with only PS access, the information stored in the S-CSCF is as follows:

Public User ID --- Contact IP1 - CS access - Alt contact IP2

+ - Contact IP2 - PS access

+ - Contact IP3 - PS access

Note - IP1 is the ICCF IP address in case of CS access.

FIG. 3c illustrates the use of confidential identity for IP Multimedia Subsystem (IMPI) in order to identify a device. IMPIs can be retrieved from the IMSI delivered in the ICCP Registration Request (USSD MAP message), and can be populated in the existing Authorization header of the REGISTER message. The S-CSCF shall store IMPI information with the IP address of the contact that should be used for routing decisions. For example, if two devices are registered, one of which is a UE with CS and PS access, and the other is a UE that is a PC with only PS access, the information stored in the S-CSCF is as follows:

Public User ID --- Contact IP1 - CS access - IMPI1

+ - Contact IP2 - PS access - IMPI1

+ - Contact IP3 - PS access - IMPI1

Note 1 to entry: IP1 is the IP address of the ICCF in the case of CS access. Note 2 to entry: IMPI1 is retrieved from the IMSI, and IMPI2 is stored in the IMSI attached to the PC.

FIG. 4a-4d illustrate situations in which ordering in an S-CSCF is changed in accordance with an embodiment of the present invention. The S-CSCF can also use the P-Access-Network-Information to implement the rules according to the settings of the operator or user, to place contacts associated with CS-access in an order different from typical PS-access.

Currently, contact processing is based only on q value from the user. The q parameter is used to indicate the priority value of contacts for routing from the user. The present invention provides a sequencing rule that can be based on local policy in the S-CSCF and can be different, for example, depending on the time of day or for each subscriber. Possible orderings in the S-CSCF may include:

- First, a sample of the CS-access contact, and then a PS-access probe, if there is no response (Fig. 4a);

- First, a PS access contact probe, and then a CS access probe if there is no response (Fig. 4b);

- Sample of a CS-access contact only if contacts with both CS-access and PS-access are registered (if only one contact is registered, a sample of a registered contact) (Fig. 4c); and alternatively

- A sample of a PS-access contact only if contacts with both CS-access and PS-access are registered (if only one contact is registered, a sample of a registered contact) (Fig. 4d). These options should complement contact handling in the S-CSCF, which is currently based only on q-value from the user.

FIG. 5a-5d illustrate situations in which various branching actions can be taken according to an embodiment of the present invention. The S-CSCF can also use P-Access-Network-Information to implement rules to suppress branching to contacts for a single device registered over multiple accesses. The branch rule can be based on local policy in the S-CSCF and can be different, for example, depending on the time of day. Possible branching rules include:

- Branching only to the contact with the PS-access, if the user is registered in both CS-access and PS-access (Fig. 5a);

- Branching only to a contact with CS access if the user is registered in both CS access and PS access (Fig. 5b);

- First branching to the contact with the PS-access, and then to the contact CS (Fig. 5c); and

- First branching to the contact with CS access, and then branching to the contact PS (Fig. 5d). A rule can also be combined with a consecutive call so that:

- Branching only to a contact with PS-access, if the user is registered in both CS-access and PS-access. If none of the branched devices responds, request a CS access contact, and

- Branching only to a contact with CS-access, if the user is registered both in CS-access and in PS-access. If none of the branched devices responds, request a PS access contact.

The branch rule can be based on local policy in the S-CSCF and can be different, for example, depending on the time of day.

FIG. 6a-6f illustrate situations regarding various sequential ringing actions according to an embodiment of the present invention. The S-CSCF can use the P-Access-Network-Information to call contacts sequentially in the way that contacts associated with one device but with different accesses are requested sequentially before (or after) trying to call contacts pointing to other devices. In other words, possible consecutive call rules include:

1) When making a serial call to various devices, first try the contact of the PS-access, if the user is registered in both CS-access and PS-access. If there is no response:

- CS access probe to the probe of another device (Fig. 6a);

- a sample of the CS access contact after there is no answer to all consecutive calls to other devices (Fig. 6b); and

- Do not include the CS access contact (Fig. 6c);

2) When making a serial call to various devices, first try the CS-contact contact, if the user is registered in both CS-access and PS-access. If there is no response:

- a sample of PS access before requesting another device (Fig. 6d);

- a probe of the PS access contact after no answer to all consecutive calls to other devices (Fig. 6e); and

- Non-inclusion of the P-access contact (Fig. 6c);

The consecutive call rule can be based on the local policy in the S-CSCF and can be different, for example, depending on the time of day.

These parameters may be included in the P-Access-Network-Information, or may be included as a new SIP header parameter. The AS may use the contact information to distinguish between CS access and PS access to select an access domain (ADS).

In VCC 3GPP Version 7, the VCC application server implements ADS. When ADS selects PS access, the call is routed to a registered contact in PS access. When ADS selects CS access because the S-CSCF does not have a registered contact in CS access, ADS forwards the call using a suitable route number to be able to route to CS access (called the CS route number) to bypass contact processing in S -CSCF. AS VCC can recognize the PS registration status using a third-party registration mechanism when a user is registered in PS access, but must implement a specific non-IMS mechanism to recognize that the user is registered in CS access. Third-party IMS registration can also be used to determine the status of registration in CS access, which should simplify the implementation of ADS.

AS and S-CSCFs can issue CDRs including P-Access-Network-Information so that the operator can distinguish between a charging and billing scheme for PS access communication and CS access communication. P-Access-network-Information can also be included in an INVITE request when a session is established from the ICCF (not only the REGISTER message when a user logs in to CS access) to indicate that the connection is through CS access.

FIG. 7 illustrates an indication of circuit switched access to a presence server according to an embodiment of the present invention. The presence server, which is SIP AS, can also receive P-Access-Network-Information during third-party registration procedures to determine whether the user is in PS access or CS access, and can provide optimal information to observers. An “observer” in this context is a user subscribed to ICS user presence information, and he “observes” the ICS user presence status. The observer uses the presence state to determine which access should be used in order to initiate multimedia communication, so that if the user is registered in the PS access, the observer can initiate a multimedia call on the PS access (for example, speech and video on the PS access). Such an observer may reside in a UE or in a network node.

Specialists in the art should understand that the innovative ideas described in this application can be modified and varied according to a wide range of applications. Accordingly, the scope of the patented subject matter of the invention should not be limited by any of the specific exemplary ideas explained above, but rather should be defined by means of the attached claims.

Claims (14)

1. A method of registering a user equipment (UE) in an IP multimedia subsystem (IMS), comprising the steps of: sending a request to register a UE in IMS; determining whether a registration request originates from a circuit switched access network; in response to determining that the registration request originates from the circuit-switched network, a header containing information regarding the circuit-switched access network is inserted into the registration request and the registration request is sent to the IMS and the associated IMS application server. 2. The method according to claim 1, further comprising a Call Session Management Function (S-CSCF) using the information in the inserted header to implement access-dependent rules according to the settings of the IMS operator or user. 3. The method of claim 1, wherein the header is inserted into the registration request through the IMS CS management function and the header is a P-Access-Network-Information header that includes contacts associated with circuit switched access. 4. The method according to claim 3, in which the addresses of the contacts associated with the access to the circuit switched in the header are placed in the order before or after the usual contact of the access with packet switching based on local policy, time of day, or according to the profile of the subscriber. 5. The method according to claim 1, in which the identification of user equipment is performed by using the information included in the ICCP registration request, the information including a device identifier (Device ID), an alternative contact, or confidential identification data for the IP multimedia subsystem. 6. The method of claim 5, wherein the device identifier is the ICCF IP address, the alternate contact is information stored by the S-CSCF with the contact IP address, and confidential identification information for the IP multimedia subsystem is retrieved from the IMSI UE. 7. A system for registering a user equipment (UE) in an IP multimedia subsystem (IMS), comprising: a UE for sending a registration request via the IMS CS control protocol (ICCP) to IMS; IMS-related means for determining whether a registration request originates from a circuit switched access network; a function for inserting a header containing information regarding the type of circuit switched access into the registration request, if it is determined that the registration request is coming from a circuit switched network; and logic for sending the registration request to the IMS and the associated IMS application server. 8. The system of claim 7, further comprising a Call Session Management Function (S-CSCF) for using the information in the inserted header to implement access rules according to the settings of the IMS operator or user. 9. The system of claim 7, wherein the header is inserted into the registration request through the IMS CS management function (ICCF) and the header is the P-Access-Network-Information header, which includes contacts associated with circuit switched access. 10. The system according to claim 9, in which the addresses of the contacts associated with the access to the switched channels in the header are placed in the order before or after the usual contact of the access to switched packets based on the ordering rules regarding the processing of contacts according to local policy, time of day, or according to subscriber profile. 11. The system according to claim 7, in which the identification of user equipment is carried out by using the information included in the ICCP registration request, the information including a device identifier (Device ID), an alternative contact, or confidential identification data for the IP multimedia subsystem. 12. The system of claim 11, wherein the device identifier is the ICCF IP address, the alternate contact is information stored by the S-CSCF with the contact IP address, and confidential identification information for the IP multimedia subsystem is retrieved from the IMSI UE. 13. A management function for registering a user equipment (UE) in an IP multimedia subsystem (IMS), the management function comprising: means for receiving from a UE a request for registration with IMS using the IMS CS control protocol (ICCP); IMS-related means for determining whether a registration request originates from a circuit switched access network; a function for inserting a header containing information regarding the type of circuit switched access into the registration request, if it is determined that the registration request is coming from a circuit switched network; and logic for sending the registration request to the IMS and the associated IMS application server. 14. A serving call session management function (S-CSCF) in a system for registering user equipment (UEs) in an IP multimedia subsystem (IMS), the system comprising means for receiving a registration request from the UEs for IMSs using the IMS CS (ICCP) management protocol , an IMS-related means for determining whether a registration request originates from a circuit switched access network; a function for inserting a header containing information regarding the type of circuit switched access into the registration request, if it is determined that the registration request is coming from a circuit switched network; and logical means for sending the registration request to the IMS and the associated IMS application server; moreover, the S-CSCF contains means for using the information in the inserted header to implement access rules according to the settings of the IMS operator or user.

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