KR20110132963A - Method for preventing undesired "call forwarding if out of reach" and providing an immediate ring-back tone in mvoip network - Google Patents

Abstract

PURPOSE: An unnecessary shadow call forwarding preventing and fast call connecting method on mVoIP(mobile Voice over Internet Protocol) network is provided to prevent a call of a received terminal from being switched in an idle state. CONSTITUTION: A call control server receives a call connection request message(606). The call control server obtains the current state of the received terminal(607). The call control server confirms whether to be capable of receiving a call(608). The call control server performs a shadow call forwarding service(612). The call control server requests the connection of the corresponding incoming call.

Description

Method for preventing undesired “call forwarding if out of reach” and providing an immediate ring-back tone in mVoIP network}

The present invention relates to a method for preventing unnecessary shadow forwarding and providing fast ring-up tones in a mobile voice over Internet Protocol (mVoIP) network, and more particularly, to providing an mVoIP service in a wireless network, to a shadow forwarding service in an mVoIP network. By determining the current state of the subscribed terminal, the call is prevented from being switched to the shadow when the called terminal is able to receive the call, such as an idle state, and additionally, a normal ring back tone (ringback tone or The present invention relates to a method for preventing unnecessary call forwarding and providing fast ring back tone in an mVoIP network.

In addition, the mVoIP terminal in one embodiment of the present invention below is a single mode mVoIP terminal capable of accessing a portable Internet network or a WiMAX network, as well as a portable Internet network or a WiMAX network and other call access networks ( Examples include a dual mode mVoIP terminal or a tri mode mVoIP terminal that can be connected to CDMA or W-CDMA or a next-generation wireless communication network.

In the following embodiment of the present invention, when the mVoIP destination terminal is not available, the service for the call forwarding to another telephone number (other call access network phone number of the same terminal or the phone number of the other terminal) preset by the subscriber It will be referred to as "shading call forwarding service".

In the existing technology, when an mVoIP terminal registered in a call session control function (CSCF) normally moves to a shadow area, when an incoming request to the mVoIP terminal is received, the CSCF sends a call connection request message (INVITE message) to the mVoIP destination terminal. send.

However, since the mVoIP called terminal is located in the shadow area, the mVoIP called terminal does not receive the call connection request (INVITE) message, and accordingly, the CSCF determines that there is no response from the mVoIP called terminal to the call connection request message. Release the call request.

Therefore, even if the call forwarding service is registered in advance for the mVoIP terminal, the call forwarding service does not operate, and there is a problem that call forwarding is not performed for the call forwarding request. This phenomenon occurs when a call forwarding service according to a condition does not receive a response from a user of a called terminal (that is, a "No Answer" situation where a signal is received but does not answer a call) or when a call is received. If there is no response signal from the terminal occurs because it determines that the error is released.

In order to solve this problem, in a conventional shadow forwarding service, an IP Multimedia Subsystem (IMS) server (call control server is referred to as an application server in the embodiment) or a WVS (WiMAX VoIP Service) server (call control server) is shaded. If the called terminal does not respond to the call request message (INVITE) sent to the called terminal in the area (or the modem is turned off), another telephone number set in advance (registered) by the subscriber (other dialing network telephone number of the same terminal) Or the phone number of another terminal).

That is, in the prior art, when the mVoIP destination terminal is located in a shaded area, when the portable Internet modem is in an idle state, or when the mVoIP destination terminal is powered off, or the call connection request message is delayed. If the mVoIP called terminal cannot receive the call within a certain period of time, such as when the call is activated, the shadow call forwarding service is activated so that the subscriber sets a different phone number (the other call access network number of the same terminal or another terminal of the same terminal). Call forwarded the call to the number) to connect the call.

However, in the wireless network, even if the called terminal is in the coverage of the wireless communication network, if it does not communicate for a predetermined time, it is in an idle state. In this case, the called terminal wakes up to an awake state through a paging process. There is a significant delay before sending a response to the call connection request. In this case, two problems arise.

The first problem is that if the called terminal does not respond within the response waiting time set by the shadow call forwarding service, the IMS server (application server) or the WVS server (call control server) proceeds with the shadow call forwarding process. Undesired call forwarding occurs for the called terminal. In particular, the longer the paging cycle, the longer the time delay and the higher the frequency of the first problem. For reference, the shadow call forwarding time in the mobile Internet network developed by "KT" is 5 seconds and the paging cycle of the mobile Internet network is about 5.2 seconds.

The second problem is that during the delay in response to the call connection request, the caller does not hear the ring back tone or ring tone. This can cause the caller to mistake the device for failure and terminate the call connection request.

As described above, the prior art as described above, in the mVoIP network, the called terminal subscribed to the shadow call forwarding service is in a callable state, but if the response to the call connection request is delayed due to the current idle state, etc. There is a problem that the switching occurs, and also there is a problem that the caller does not hear the ring back tone (ringback tone or coloring) to terminate the call connection request during the delay in response to the call connection request, at least any of these problems It is an object of the present invention to solve one.

Accordingly, in the present invention, in providing a mVoIP service in a mobile Internet network, the current price of the called terminal subscribed to the shadow call forwarding service in the mVoIP network is determined so that the corresponding price can be received when the called terminal is able to receive the current idle state. An object of the present invention is to provide a shadow call forwarding prevention method in an mVoIP network to prevent shadow call forwarding.

In addition, the present invention provides a mVoIP service in the mobile Internet network, when the called terminal is able to receive the current state of the idle (idle) by determining the current state of the called terminal subscribed to the shadow call forwarding service in the mVoIP network Another object of the present invention is to provide an unnecessary method of preventing shadow forwarding and providing fast ring back tone in an mVoIP network to prevent call forwarding and to provide normal ring back tone or coloring without delay to the calling terminal. .

In addition, the present invention provides an mVoIP service in a mobile Internet network, and determines the current state of a called terminal subscribed to the shadow call forwarding service in the mVoIP network, and is called when the called terminal is able to receive the call, such as an idle state. Another object of the present invention is to provide a method for providing a quick ring back tone in an mVoIP network to provide a normal ring back tone (ringback tone or coloring) without delay to the terminal.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

In the method of the present invention for achieving the above object, in the shadow call forwarding prevention method, when the call control server receives a call connection request message, the state checking step of acquiring the current state of the called terminal to check whether the incoming state ; Performing a shadow call forwarding service if the current state of the called terminal is incapable of receiving a call as a result of the checking of the state checking step; And if the current state of the called terminal is a callable state, as a result of the checking of the state, the call control server prevents the incoming call from being shadowed and then requests the connection of the incoming call.

In addition, in the method of the present invention for achieving the other object, if the current state of the called terminal is a callable state, the call control server on the call terminal request the call connection request on behalf of the called terminal; The method may further include delivering a first call enabled message in response to the message to provide a ring back tone to the calling terminal.

In addition, the method of the present invention for achieving the other object, the call control server further comprises the step of discarding the second call available message received through the terminating CSCF from the terminating terminal.

On the other hand, the method of the present invention for achieving the above another object, in the method for providing a call connection sound, when the call control server receives a call connection request message, to determine whether the incoming state by receiving the current state of the called terminal; Status check step; Performing a shadow call forwarding service if the current state of the called terminal is incapable of receiving a call as a result of the checking of the state checking step; And when the current state of the called terminal is a callable state, as a result of the checking of the state, the call control server delivers the first call available message in response to the call connection request message on behalf of the called terminal. And providing a ring back tone to the terminal.

In addition, the method of the present invention for achieving the another object, the call control server further comprises the step of discarding the second call available message received through the incoming CSCF from the called terminal.

On the other hand, another method of the present invention for achieving the above object, in the shadow call forwarding prevention method, when the call control server receives a call connection request message, the status checking step of obtaining and confirming the current state of the called terminal; If the current state of the called terminal is an ACTIVE state as a result of the checking of the state checking step, processing the incoming call; Performing a corresponding call termination or shadow forwarding service when the current state of the called terminal is not in service (NOT-IN-SERVICE) as a result of the checking of the state checking step; And if the current state of the called terminal is in an idle state or an in-service state, the call control server adjusts a call connection request transaction timeout to shade the corresponding call. Processing the incoming call after preventing it from being forwarded.

In addition, another method of the present invention for achieving the other object, if the current state of the called terminal is the idle state (IDLE) state, as a result of the check of the status check step, the call control server on behalf of the called terminal; The method may further include delivering a first call enabled message in response to the call connection request message to provide a ring back tone to the calling terminal.

In addition, another method of the present invention for achieving the other object, the call control server further comprises the step of discarding the second call available message received from the called terminal.

In addition, another method of the present invention for achieving the other object, if the current state of the called terminal is in the service (IN-SERVICE) state, as a result of the check of the status check step, the call control server is the called terminal In response to the call connection request message in place of the first call available message further comprises the step of providing a call ring tone to the calling terminal.

On the other hand, another method of the present invention for achieving the above object, In the method for providing a ring back tone, the call control server receives a call connection request message, the status checking step of obtaining and confirming the current state of the called terminal; If the current state of the called terminal is an ACTIVE state as a result of the checking of the state checking step, processing the incoming call; Performing a corresponding call termination or shadow forwarding service when the current state of the called terminal is not in service (NOT-IN-SERVICE) as a result of the checking of the state checking step; And if the current state of the called terminal is in the idle state as a result of the checking of the state, the call control server delivers a first call available message in response to the call connection request message on behalf of the called terminal. To provide a ring tone to the calling terminal.

In addition, another method of the present invention for achieving the another object, the call control server further comprises the step of discarding the second call available message received from the called terminal.

In addition, another method of the present invention for achieving the another object is that, if the current state of the called terminal is in the service (IN-SERVICE) state, as a result of the check of the state checking step, the call control server the incoming call And transmitting the first call enabled message in response to the call connection request message on behalf of a terminal to provide a call connection tone to the calling terminal.

As such, the present invention prevents shadow call forwarding from occurring when a response to a call connection request is delayed due to reasons such as an idle state, although a called terminal subscribed to a shadow call forwarding service in an mVoIP network is in a callable state. In order to determine the current state of the called terminal to prevent the corresponding call connection request call is shaded call forwarding processing, and additionally provides a normal ring back tone (ringback tone or coloring) without delay to the calling terminal.

The present invention as described above, in providing a mVoIP service in a wireless network, when the called terminal is able to receive the current idle state, such as by determining the current state of the called terminal subscribed to the shadow call forwarding service in the mVoIP network There is an effect that can prevent the call from being transferred to the shadow.

That is, in providing the mVoIP service in the wireless network, the present invention does not mistake a terminating terminal subscribed to the shadow forwarding service in the mVoIP network as being out of coverage of the wireless communication network (in a shaded area) so that a normal call service is provided. Can be provided.

In addition, the present invention provides an mVoIP service in a wireless network, and determines the current state of the called terminal subscribed to the shadow call forwarding service in the mVoIP network to determine the current state of the called terminal when the called terminal is currently in the idle (idle) state, etc. It can provide normal ring back tone or ring tone without delay.

That is, the present invention allows the caller to hear a ring back tone (ringback tone or coloring) without delay even when the called terminal subscribed to the shadow call forwarding service in the mVoIP network is currently idle. Make sure you wait in peace without closing the request.

Accordingly, the present invention can improve the success rate of the call, thereby improving the convenience of the subscriber as well as increase the mVoIP call revenue of the telecommunications operator.

In addition, the present invention, if the destination terminal is not registered in the shadow call forwarding service does not wait for the incoming WVS server timeout (SIP INVITE) transaction timeout immediately send an error message to the originating network quickly The call can be terminated.

1 is an example of an IMS-based mVoIP network to which the present invention is applied;
2 is a flowchart illustrating a signal processing procedure when a called terminal registered to a shadow call forwarding service normally responds to an incoming call;
3 is a flowchart illustrating a signal processing procedure when a called terminal registered with a shadow forwarding service is unanswered to an incoming call;
4 is a flowchart illustrating a signal processing procedure when a called terminal registered to a shadow forwarding service is in a deregistered state or temporarily unable to make a call;
5 is a flowchart illustrating a signal processing procedure in a case where a called terminal registered to a shadow forwarding service according to the present invention is currently in an idle state;
6 is a flowchart illustrating an exemplary method for preventing unnecessary call forwarding and providing fast ring back tone in an mVoIP network according to the present invention;
7 is a flowchart illustrating another embodiment of a call connection processing procedure to a terminating terminal disconnected from a network;
8 is a flowchart illustrating another embodiment of a call connection processing procedure in a called network when a called terminal subscribed to a shadow call forwarding service is in an idle mode.
9 is another flowchart illustrating a call connection processing procedure when a called terminal is not in service in an mVoIP network according to the present invention;
10 is a flowchart illustrating another embodiment of a call connection processing procedure when a called terminal is in an idle mode according to the present invention;
11 is a flowchart illustrating another embodiment of a method for preventing unnecessary call forwarding and providing a quick ring back tone in an mVoIP network according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings, It can be easily carried out. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

And throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "electrically connected" with another part in between. Also, when a component is referred to as " comprising "or" comprising ", it does not exclude other components unless specifically stated to the contrary .

1 is an example of an IMS-based mVoIP network to which the present invention is applied.

As shown in FIG. 1, an IMS-based mVoIP network to which the present invention is applied consists of a mobile Internet (WiBro) network and an IMS network by way of example. It can provide VoIP-based call services (eg, voice call service, video call service) to the terminal.

In this case, the portable Internet network may include an mVoIP terminal, a base station (RAS), a base station controller (ACR: access control router), a terminal access authentication function, and a charging information collection function for packet charging. Authorization, Accounting) servers (not shown) and the like, and the IMS network includes Proxy-Call Session Control Function (P-CSCF), Interrogating-CSCF (I-CSCF), and Serving-CSCF (S-CSCF). It includes CSCF, PCRF (Policy and Charging Rule Function, also known as QoS Manager (QM)), including the application server (AS), MGCF (Media Gateway Control Function) for providing IMS application services, including.

In addition, MGW for interworking with IMS network and other networks (mobile communication network and wired telephone network) is provided. Although not shown in the drawing, the IMS network includes HSS (Home Subscriber Server) for voice service authentication and data additional service authentication. HDS (Home Digital Service) is further provided.

The mobile communication network (WCDMA, CDMA, GSM) linked to the IMS network includes an MSC, a BSC, a BTS, a mobile communication terminal, and the like, and a wired telephone network (PSTN) includes an exchanger and a wired telephone.

Next, the components will be described in more detail.

The Call Session Control Function (CSCF) is a system in charge of a part related to call processing among functions of the IMS, and includes an incoming call gateway (ICGW), a call control function (CCF), a serving profile database (SPD), and an address handling (AH). )

Here, the incoming call gateway (ICGW) operates as the first entry point and performs routing for the input call. In addition, ICGW performs service triggering on input calls such as call screening and forwarding, and inquires about address handling (AH) and communication with Home Subscriber Server (HSS).

The CCF (Call Control Function) is responsible for call setup and termination, status / event management, interaction with multimedia resource functions (MRF) for multiparty services, call event reporting for billing, and reception and processing of application level registrations. .

The Serving Profile Database (SPD) manages user profile information by communicating with the HSS of the home domain, and performs a function similar to the VLR (Visitor Location Register) of the existing network that informs the home domain of the user's first access.

Address handling (AH) performs the function of parsing, translating, and modifying addresses, and provides address portability.

Since the Call Session Control Function (CSCF) performs different functions depending on the network where the subscriber is located, the Proxy-CSCF (P-CSCF), Interrogating CSCF (I-CSCF), and S- Logically divided into CSCFs (Serving CSCFs), for example, the function of guaranteeing the Quality of Service (QoS) in conjunction with the PCRF is performed in the P-CSCF.

On the other hand, PCRF (Policy and Charging Rule Function) is a system that provides service-based quality of service (QoS) policy setting function and flow-based charging rule (QoS) function. It collects basic service information, verifies the authority of the service according to the policy decision of the network operator, and delivers the quality assurance (QoS) policy and the charging policy to allocate network bandwidth to the network access system.

Meanwhile, a base station controller (ACR: Access Control Router) refers to a component that controls a terminal (mVoIP terminal) and a base station (RAS) and routes IP packets in a portable Internet network.

From the standpoint of data traffic, the base station controller (ACR) can be viewed as a router (access control router), and manages several base stations (RAS) underneath.

The base station controller (ACR) processes air interface control signals, bearer service traffic, and the like between a radio access station (RAS) and a core network (Core Network).

And base station controller (ACR) is interworking function with base station (RAS), call connection setting function, location management (mobility management) function of wireless terminal (mVoIP terminal), authentication and security function, charging and statistics Creates and notifies information and manages IP QoS.

On the other hand, a base station (RAS: Radio Access Station) refers to a portable Internet network component that terminates a wired network and transmits and receives a wireless terminal (mVoIP terminal) through a wireless interface.

Looking at the type by function, the serving base station (Serving RAS) is a base station that the mobile terminal is currently being serviced, a base station that has recently registered a wireless terminal (mVoIP terminal). The target base station (Target RAS) is a destination base station to be handed over by a wireless terminal (mVoIP terminal), and a base station to which a wireless terminal (mVoIP terminal) intends to register at the end of the handover. Neighbor RAS refers to a base station adjacent to the serving base station. In addition, there are a detected base station (Detected RAS), a selected base station (Selected RAS).

And the base station (RAS) is a radio signal transmission and reception function, modulation and demodulation signal processing function, packet retransmission function, packet scheduling function, radio bandwidth allocation function, ranging function, connection control functions such as packet call connection establishment / maintenance / release, and hand It performs over control function.

The main requirements of the base station (RAS) are frequency efficiency, transmission speed in terms of service, QoS parameters (jitter, latency, packet loss rate, transmission rate, etc.), handover, and the like.

Meanwhile, a media gateway (MGW) refers to a device that performs media processing and conversion between a circuit switched network and a packet switched network. That is, the media gateway MGW converts a voice signal in the form of a packet (IP packet, etc.) made in the Internet into a PCM or the like used in a public telephone network (wired telephone network) or vice versa.

In addition, the media gateway (MGW) has a function of converting a compressed signal for packetization of a voice signal or vice versa, an echo cancellation function of a voice caused by a delay, a reception of a digit, and a forwarding function of a fax. It converts TDM-based traffic into IP or ATM packets.

The media gateway is linked with a soft switch and a control protocol for call control between the media gateways.

In addition, the types are classified according to the interface type and the location where they are arranged. The Access Media Gateway supports access to a packet switched network such as VoIP in a private switched network. The trunk media gateway connects the circuit switched network with the packet switched network. The Residential Media Gateway also provides an analog line in the home with access to the packet network.

Meanwhile, MGCF (Media Gateway Control Function) refers to a network element that controls multiple media gateways for intelligent call control.

To implement this, call processing with the existing circuit network is connected to MGCF through SGW (Signalling Gateway) to perform call processing control function, and control the media gateway (MGW: Media Gateway) to be connected by translating call number in MGCF. It assigns IP addresses / UDP ports (User Datagram Protocol Ports) to be connected between media gateways, and manages the corresponding resources such as compression necessary to make IP packets from end to end, thereby interconnecting voice traffic delivered to media gateways.

In addition, MGCF is a concept that separates the signaling network and the transmission network by No. 7 structure like the existing PSTN / N-ISDN on the Internet, and is also called a softswitch or call agent.

FIG. 2 is a flowchart illustrating a signal processing procedure when a called terminal registered to a shadow call forwarding service normally responds to an incoming call.

First, the originating terminal A forwards a call connection request (INVITE B) message for connecting a call to the called terminal B (terminal registered in the call forwarding service) to the calling CSCF (201), and in response thereto, from the calling CSCF. Receive a 100 Trying message (202).

In the outgoing CSCF, the called terminal B acquires the received incoming CSCF and transmits an INVITE B message to the called CSCF (203), and receives a 100 Trying message from the called CSCF in response. (204)

In addition, the incoming CSCF determines that the called terminal B is a subscriber registered with the shadow forwarding service, and sends a call connection request (INVITE B) message to an application server (AS: Application Server, a call control server for controlling a shadow forwarding call). (205), and in response (206) receives a 100 Trying message from the application server (AS).

The application server (AS) starts the shadow call forwarding timer and sends an INVITE B message back to the incoming CSCF (207), and receives a 100 Trying message from the incoming CSCF in response. (208).

The destination CSCF forwards the call connection request (INVITE B) message received from the application server (AS) to the destination terminal B (209), whereby the destination terminal B rings and a 180 ringing message. The callable message is forwarded to the incoming CSCF (210).

Then, the incoming CSCF forwards the 180 ringing message to the application server AS (211), and the application server AS forwards the 180 ringing message back to the destination CSCF (212). . At this time, the application server AS determines whether a 180 ringing message is received in response to the INVITE B message within a predetermined response waiting time (within the response waiting time set in the call forwarding timer). Check to see if the called terminal B responds. At this time, the application server AS determines that the called terminal B can receive the call if there is a response from the called terminal B within the predetermined response waiting time.

The called CSCF forwards the 180 ringing message to the calling CSCF if the called terminal B can receive the call (213), and accordingly, the calling CSCF forwards the 180 ringing message to the calling terminal A (214). ).

When the called party answers the call [Hook-Off], the called terminal B transmits a call connection response (200 OK) message to the called CSCF in response to the INVITE B message (215).

Then, the incoming CSCF forwards the call connection response 200 OK message to the application server AS 216, and accordingly, the application server AS forwards the call connection response 200 OK message back to the destination CSCF ( 217). The incoming CSCF forwards the call connection response (200 OK) message to the calling CSCF (218), and accordingly the calling CSCF forwards the call connection response (200 OK) message to the calling terminal A (219).

Accordingly, a call path is established between the calling terminal A and the called terminal B to make a call (220).

3 is a flowchart illustrating an example of a signal processing procedure when a called terminal registered with a shadow forwarding service is unanswered to an incoming call.

First, the originating terminal A forwards a call connection request (INVITE B) message for connecting the call to the called terminal B (terminal registered in the call forwarding service) to the calling CSCF (301), and in response, from the calling CSCF. Receive a 100 Trying message (302).

In the outgoing CSCF, the called terminal B acquires the received incoming CSCF and transmits an INVITE B message to the called CSCF (303), and receives a 100 Trying message from the called CSCF in response. (304)

In addition, the called CSCF determines that the called terminal B is a subscriber registered with the shadow call forwarding service, and transmits a call connection request (INVITE B) message to an application server (AS) (305), in response to the application server. A 100 Trying message is received from the AS (306).

The application server (AS) starts the shadow call forwarding timer and sends a call connection request (INVITE B) message back to the incoming CSCF (307), and receives a 100 Trying message from the incoming CSCF in response. (308)

The called CSCF forwards the INVITE B message received from the application server AS to the called terminal B. However, the called terminal B is located in the shadow area and the INVITE message is sent to the called terminal B. (309) Accordingly, the called CSCF does not receive the 180 ringing message from the called terminal B, and also does not transmit the 180 ringing message to the application server AS.

On the other hand, the application server AS, after the call connection request (INVITE B) message of the "307" process, the call connection request from the incoming CSCF within the predetermined response waiting time (within the response waiting time set in the call forwarding timer) In response to the INVITE B) message, it is checked whether a 180 ringing message is received to determine whether the called terminal B responds. At this time, the application server AS determines that the called terminal B is impossible to receive in the shaded area if there is no response from the called terminal B during the predetermined response waiting time. Accordingly, the application server AS drives the shadow forwarding service (310) to deliver a "181 Call is being forwarded message to the forwarding CSCF" to the incoming CSCF (310), and accordingly The CSCF forwards the "181 Call is being forwarded message to the forwarding phone number" message to the outgoing CSCF (312), whereby the outgoing CSCF sends the "181 Call is being forwarded to the forwarding phone number." Message) to the originating terminal A (313). Accordingly, the calling subscriber waits without hanging up. However, since the caller does not hear any sound during the response waiting time set in the shadow call forwarding timer, the response waiting time of the shadow call forwarding timer is generally set to 5 seconds.

In the application server (AS), if the called terminal B is unanswered in the shadow area as described above, the call is connected to the called CSCF to transfer the call to the terminal (called terminal C) registered in the shadow call forwarding service in advance. It forwards a request (INVITE C) message (314) and receives (315) a 100 Trying message from the incoming CSCF in response.

In addition, the called CSCF checks the system (MGCF, other CSCF, etc.) accommodated by the called terminal C, and transmits a call connection request (INVITE C) message to the called terminal C through the corresponding system (316). Accordingly, the called terminal C rings and sends a 180 ringing message (callable message) to the called CSCF (not shown in the figure).

When the called party receives a call [Hook-Off], the called terminal C transmits a call connection response (200 OK) message to the called CSCF in response to the INVITE C message (317).

Then, the incoming CSCF forwards the call connection response 200 OK message to the application server AS (318), and thus the application server AS forwards the call connection response 200 OK message back to the destination CSCF ( 319). The incoming CSCF forwards the call connection response (200 OK) message to the calling CSCF (320), and accordingly, the calling CSCF forwards the call connection response (200 OK) message to the calling terminal A (321).

Accordingly, a call path is established between the calling terminal A and the called terminal C to make a call (322).

FIG. 4 is a flowchart illustrating a signal processing procedure when a called terminal registered to a shadow call forwarding service is deregistered or temporarily unable to make a call.

First, the calling terminal A transmits a call connection request (INVITE B) message for connecting a call to the called terminal B (the terminal registered with the call forwarding service) to the calling CSCF (401), and in response thereto, from the calling CSCF. Receive a 100 Trying message (402).

In the outgoing CSCF, the called terminal B acquires the received incoming CSCF and transmits an INVITE B message to the called CSCF (403), and receives a 100 Trying message from the called CSCF in response. (404).

In addition, the called CSCF determines that the called terminal B is a subscriber registered with the shadow call forwarding service, and transmits a call connection request (INVITE B) message to an application server (AS) (405), and in response, the application server. A 100 Trying message is received from the AS (406).

In operation 407, the application server AS starts the shadow forwarding timer and transmits a call connection request (INVITE B) message to the incoming CSCF.

Then, the incoming CSCF receiving the call connection request (INVITE B) message from the application server (AS) checks the current state of the called terminal B, and if it is determined that the called terminal B is temporarily unable to make a temporary call ( A message 480 is sent 408 to the application server AS. Here, the state in which the called terminal B cannot make a call temporarily includes a case where the called terminal B is located in a shadowed area and the registration is released from the CSCF, or the called terminal B cannot make a call for other reasons.

If the application server (AS) receives a 480 Temporarily Unavailable message in response to a call connection request (INVITE B) message of step 407, the application server AS starts a call forwarding service (409). Forward 181 Call is being forwarded message to the incoming CSCF (410), whereby the incoming CSCF sends a "181 Call is being forwarded message" to the forwarding phone number. Forwarding to the CSCF (411), and accordingly the originating CSCF forwards the "181 Call is being forwarded message to the forwarding phone number" message to the calling terminal A (412). Accordingly, the calling subscriber waits without hanging up.

In the application server AS, the incoming CSCF is used to transfer the call to the terminal (called terminal C) registered in the shadow forwarding service in advance when the called terminal B is temporarily unavailable in the shadow area. It forwards a call connection request (INVITE C) message (413), and receives a 100 Trying message from the incoming CSCF in response (414).

In addition, the called CSCF checks the system (MGCF, other CSCF, etc.) accommodated by the called terminal C, and transmits a call connection request (INVITE C) message to the called terminal C through the corresponding system (415). Accordingly, the called terminal C rings and sends a 180 ringing message (callable message) to the called CSCF (not shown in the figure).

When the called subscriber receives a call [Hook-Off], the called terminal C transmits a call connection response (200 OK) message to the called CSCF in response to the INVITE C message (416).

Then, the incoming CSCF forwards the call connection response 200 OK message to the application server AS 417, and accordingly, the application server AS forwards the call connection response 200 OK message back to the incoming CSCF ( 418). The incoming CSCF forwards the call connection response (200 OK) message to the calling CSCF (419), and accordingly the calling CSCF forwards the call connection response (200 OK) message to the calling terminal A (420).

Accordingly, a call path is established between the calling terminal A and the called terminal C to make a call (421).

As described above, in the shadow forwarding service, when the mVoIP destination terminal is located in the shadow area, when the mobile modem is in an idle state, or when the mVoIP destination terminal is turned off, or a call connection request message If the mVoIP called terminal cannot receive the call, such as when the call is delayed, etc., the call forwarding service is activated and the other phone number set in advance (registered) by the subscriber (other call network number of the same terminal or other The phone number is connected to the call by the call forwarding).

However, the above-mentioned shadow call forwarding service is available when the called terminal subscribed to the shadow call forwarding service in the mVoIP network is in a callable state but the response to the call connection request is delayed due to the current idle state. In addition, the caller does not hear the ring back tone (ringback tone or coloring) during the time delay in response to the call connection request, thereby terminating the call connection request.

Therefore, when the called terminal subscribed to the shadow call forwarding service is currently in the idle (idle) or awake (awake) state, such as a state that can be called to the call forward to prevent the shadow call forward and provide a ring back tone. This will be described in detail with reference to FIGS. 5 and 6 as follows.

FIG. 5 is a flowchart illustrating a signal processing procedure in a case where a called terminal registered to a shadow forwarding service according to the present invention is currently in an idle state.

First, the calling terminal A transmits a call connection request (INVITE B) message for connecting a call to the called terminal B (the terminal registered with the call forwarding service) to the calling CSCF (501), and in response to the calling CSCF. Receive a 100 Trying message (502).

In the outgoing CSCF, the called terminal B acquires the received incoming CSCF and transmits an INVITE B message to the called CSCF (503), and receives a 100 Trying message from the called CSCF in response. (504).

In addition, the called CSCF determines that the called terminal B is a subscriber registered with the shadow call forwarding service, and transmits a call connection request (INVITE B) message to an application server (AS) (505), in response to the application server. A 100 Trying message is received from the AS (506).

The application server AS obtains (looks up) the current state of the called terminal B (507). That is, the application server AS interworks with a system that knows the current state of the terminal in the mobile Internet network (for example, base station controller (ACR), LBS server, AAA server, USI server, QM server, etc.) A state (awake state, idle state, disconnected state, etc.) is acquired (viewed) (507).

The application server AS again transmits a call connection request (INVITE B) message to the destination CSCF (508), and receives a 100 Trying message from the destination CSCF in response (509).

The called CSCF forwards the call connection request (INVITE B) message received from the application server (AS) to the called terminal B (510), but ringing 180 for a predetermined time when the called terminal B is currently idle. (180 Ringing) message will not be sent to the destination CSCF. Accordingly, the called CSCF may not receive a 180 ringing message from the called terminal B for a predetermined time and may not transmit the 180 ringing message to the application server AS for a predetermined time.

Therefore, in the application server AS, as a result of acquiring the current state of the called terminal B (507), and when the called terminal B is in the idle state (511), a response to the immediate call connection request on behalf of the called terminal B In step 512, a 180 ringing message is delivered to the called CSCF. Here, even when the called terminal B is in the awake state, it can be implemented to deliver a 180 ringing message to the called CSCF in response to the call connection request immediately on behalf of the called terminal B, but the called terminal B Is awake and can respond immediately, so you don't have to send a 180 Ringing message to the incoming CSCF instead.

The called CSCF then forwards the 180 Ringing message to the calling CSCF (513), and accordingly the calling CSCF forwards the 180 Ringing message to the calling terminal A (514). Accordingly, ringback tone or coloring occurs to the calling party so that the calling party waits without hanging up.

That is, even when the called terminal B is subscribed to the shadow call forwarding service, if the called terminal B is able to receive the call, such as an idle state or an awake state, it is not in the shadow area, so the call connection request (INVITE B ) Even if the response to the message is delayed, the call is not shadowed and the normal ring back tone or coloring is provided to the calling terminal without delay.

On the other hand, after the called terminal B wakes up in an idle state or the like, a ring is ringed in response to the INVITE B message of the “510” process and a 180 ringing message (call) Available message) is forwarded to the destination CSCF (515). Then, the incoming CSCF forwards a 180 ringing message to the application server (AS) (516), but the application server (AS) 180 ringing in response to the call connection request in step 512. ) Since the message is delivered to the called CSCF, the 180 ringing message (callable message) received in step 516 is discarded.

When the called party receives a call [Hook-Off], the called terminal B transmits a call connection response (200 OK) message to the called CSCF in response to the INVITE B message (step 517).

Then, the incoming CSCF forwards the call connection response 200 OK message to the application server AS (518), and accordingly, the application server AS forwards the call connection response 200 OK message back to the destination CSCF ( 519). The incoming CSCF forwards the call connection response (200 OK) message to the calling CSCF (520), and accordingly sends the call connection response (200 OK) message to the calling terminal A (521).

Accordingly, a call path is established between the calling terminal A and the called terminal B to make a call (522).

On the other hand, after the application server (AS) transfers the call connection request (INVITE B) message to the incoming CSCF (508), the shadow call forwarding timer (T1) is driven to wait for a response within a certain time. This is because, since the state of the called terminal B may continuously change, there may be no response when the connection is momentarily terminated in the idle state. However, in general, because the called party B knows to give a response immediately if it is in the awake state or to respond after waking if it is in the idle state, the waiting time (for example, 10 seconds) is relatively longer than the conventional shadow call forwarding timer. You can wait for a response by setting. The sender can also wait because the 180 ringing message has already been sent instead. If there is no response within a predetermined time set in the shadow forwarding timer T1, the shadow forwarding service is driven (see FIG. 6 to be described later).

6 is a flowchart illustrating a method for preventing unnecessary call forwarding and providing a quick ring back tone in an mVoIP network according to the present invention.

First, when the called CSCF receives an INVITE B message from the calling terminal A through the calling CSCF for connecting a call to the called terminal B (the terminal registered with the call forwarding service) (601), the HSS (Home) Subscriber Server) to query the caller profile (602) to determine whether the caller ID registered in the shadow call forwarding service (shaded call forwarding registration number) (603).

As a result of the checking (603), if the called number is not the number registered in the shadow call forwarding service, the call processing proceeds in a known conventional manner (604). The call connection request (INVITE B) message is transmitted to the server (AS: Application Server) (605). Accordingly, the application server (AS) receives the call connection request (INVITE B) message from the incoming CSCF (606).

Then, when receiving a call connection request message from the called CSCF, the application server AS obtains (looks up) the current state of the called terminal B (607) and confirms the current state of the called terminal B (608). That is, the application server AS interworks with a system that knows the current state of the terminal in the mobile Internet network (for example, base station controller (ACR), LBS server, AAA server, USI server, QM server, etc.) A state (awake state, idle state, disconnected state, etc.) is obtained (viewed) (607) and the current state of the called terminal B is checked (608).

As a result of the check 608, if the current state of the called terminal B is an awake state, it transmits a call connection request (INVITE B) message to the called CSCF (609) and drives a shaded call forward timer (T1: designated response wait time). When a 180 Ringing message is received from the called CSCF within the predetermined response waiting time (that is, when there is a response within the predetermined response waiting time from the called terminal B for the incoming call) (610), the application server (AS) In step 611, the shadowed call forwarding timer T1 is stopped and a 180 ringing message is transmitted to the called CSCF to process the call between the calling terminal A and the called terminal B (611).

On the other hand, if the check result 608, the current state of the destination terminal B is not connected (that is, when the destination terminal B is not registered or temporarily unavailable), the application server (AS) in the shadow call forwarding service In operation 612, the message “181 Call is being forwarded” is transmitted to the caller CSCF (613). In addition, the application server AS transfers the corresponding call to the terminal (receiving terminal C) registered in the shadow forwarding service in advance in the subscriber database (DB). Number 614) and transmits a call connection request (INVITE C) message with the retrieved shaded call forwarding phone number to the called CSCF (615) to proceed with call processing between the calling terminal A and the called terminal C ( 616).

On the other hand, if the check result 608, if the current state of the destination terminal B is in the idle state (IDle), the application server (AS) delivers a call connection request (INVITE B) message to the destination CSCF (617) and the shadow call forward timer ( T1) and transmits a 180 ringing message to the destination CSCF in response to an immediate call connection request on behalf of the destination terminal B, and 180 ringing received afterwards through the destination CSCF from the destination terminal B. The message is discarded (618). The application server AS stops the shadow call forwarding timer T1 according to the call connection response 200 OK message from the called CSCF and proceeds with call processing between the calling terminal A and the called terminal B (619).

That is, even when the called terminal B is subscribed to the shadow call forwarding service, if the called terminal B is able to receive the call, such as an idle state or an awake state, it is not in the shadow area, so the call connection request (INVITE B ) Even if the response to the message is delayed, the call is not shadowed and the normal ring back tone or coloring is provided to the calling terminal without delay.

The above-described embodiment (FIGS. 1 to 6) has described an application example in the IMS-based mVoIP service, and another embodiment to be described below will be described in the application example in the non-IMS-based mVoIP service. At this time, in another embodiment, a case in which a home AAA server is used to query the network connection state (the current state of the called terminal) of the called terminal B will be described as an example. Although WiMAX) network will be described as an example, it will be appreciated that the present invention is not limited thereto.

For reference, one of the differences between the non-IMS network and the IMS network is that in the IMS network, basic call processing is handled in a CSCF that is divided into P-CSCF, S-CSCF, and I-CSCF, and application-specific call processing (that is, In order to control shadowed incoming call, an additional application server (AS: Application Server, call control server to control shadowed incoming call) is configured to perform call processing, but all operations are performed in non-IMS network. SIP (Session Initiation Protocol) server (meaning the WVS server of another embodiment described later) can be processed.

Next, an example of a conventional call connection processing procedure in which state information of a terminal is not utilized will be described with reference to FIGS. 7 and 8.

7 is a flowchart illustrating another embodiment of a call connection processing procedure for a called terminal disconnected from a network.

In the state in which the terminating terminal B is SIP registered with the terminating WVS server (SIP server) 701, the network access termination procedure may be performed because of leaving service coverage or abnormal termination or unexpected restart of the base station without removing the SIP registration ( 702). FIG. 7 exemplarily illustrates a call connection procedure in a non-IMS based VoIP network when the network connection is disconnected as described above.

First, the calling terminal A transmits a SIP INVITE Request message for connecting a call (call) to the called terminal B to the calling WVS server in which the calling terminal A is registered (703).

Then, the originating WVS server transmits a SIP 100 (Trying) Provisional Response message to the originating terminal A in response to the SIP INVITE Request message (704). .

The originating WVS server acquires an incoming WVS server in which the called terminal B is accommodated and transmits the SIP INVITE Request message to the called WVS server (705).

Then, the incoming WVS server sends a SIP 100 (Trying) Provisional Response message to the originating WVS server in response to the SIP INVITE Request message (706). .

The incoming WVS server transmits the SIP INVITE Request message to the called terminal B (707) and drives the SIP timer A (T1 = 500 ms). For example, the SIP standard [RFC 3261] uses SIP timer A to resend a SIP INVITE Request message, and initially sets the T1 value (500 ms) corresponding to the round trip time (RTT). It is defined. However, since the incoming terminal B is not connected to the network, the call connection request message is transmitted only to the radio access network 2 (ASN / A-PCEF2) and is not received by the called terminal B. If the called terminal B is in an idle state, radio access network 2 (ASN / A-PCEF2) will perform a paging procedure so that the called terminal B enters the network again.

Meanwhile, when the SIP timer A (T1 = 500ms) expires, the called WVS server retransmits the SIP INVITE Request message to the called terminal B (708) and drives the SIP timer A (T1 * 2).

When the SIP timer A (T1 * 2) expires again, the called WVS server retransmits the SIP INVITE Request message to the called terminal B (709) and drives the SIP timer A (T1 * 4). This process is repeated until the SIP timer B expires. Here, the SIP timer B is set to T1 * 64 and means a SIP INVITE transaction timeout timer.

Meanwhile, when the SIP timer B (T1 * 64) expires, the destination WVS server transmits a SIP 408 Request Timeout Response message to the originating WVS server (710).

Then, the originating WVS server transmits the SIP 408 Request Timeout Response message to the originating terminal A (711).

Then, the originating terminal A transmits a SIP ACK Request message to the originating WVS server in response to the SIP 408 Request Timeout Response message (712).

Then, the originating WVS server transmits the SIP ACK Request message to the destination WVS server (713).

At this time, between the process "704" and "711", the user of the calling terminal A may hang up the call because it does not hear the ring back tone or coloring. The ring back tone is played only when the calling terminal A receives a SIP 180 (Ringing) Provisional Response (SIP 180) message (callable message). Based on the timer initial value in the SIP standard [RFC 3261], the timeout value of the SIP timer B is too long. In an actual implementation, the maximum number of retransmissions of the SIP INVITE Request message may be limited or the call connection request ( SIP INVITE) By defining and using a separate short timer for transaction timeout, it is faster to determine whether to terminate or proceed with the incoming call. For example, stop retransmission immediately after retransmission of two or three SIP INVITE Request messages, and the destination terminal B is out of coverage of the wireless communication network (e.g. WiMAX network) (in the shaded area). Judges and handles the call. If the called terminal B is subscribed to the shadow call forwarding service, the called call is transferred to another telephone number (other call access network telephone number of the same terminal or the telephone number of another terminal) that the subscriber has set (registered) in advance. Call forwarding is connected. This shaded call forwarding scenario is illustrated in FIG. 8, which illustrates a case where the called terminal B is in an idle state.

8 is a flowchart illustrating another embodiment of a call connection processing procedure in a called network when a called terminal subscribed to a shadow call forwarding service is in an idle mode.

First, the called terminal B subscribed to the shadow forwarding service is in an idle mode (801).

At this time, the destination WVS server receives a SIP INVITE Request message from the originating network for connecting a call to the destination terminal B (terminal registered to the call forwarding service).

The incoming WVS server transmits a SIP 100 (Trying) Provisional Response message to the calling network in response to the SIP INVITE Request message (803).

The destination WVS server transmits the SIP INVITE Request message to the destination terminal B side (804) and drives the SIP timer A (T1 = 500ms). The incoming WVS server confirms that the called terminal B is subscribed to the shadow call forwarding service and drives the SIP timer CF1 (for example, 3 to 5 sec). At this time, when the wireless access network 2 receives the downlink packet destined for the called terminal B, that is, a SIP INVITE Request message of the "804" process, the called terminal B is in the idle state 801 and enters the wireless network again. To perform a paging procedure to return to the active mode.

On the other hand, when the incoming WVS server expires SIP timer A (T1 = 500ms, call connection request message retransmission timer), the incoming WVS server retransmits the SIP INVITE Request message to the destination terminal B (805) and SIP timer A (T1). * 2).

When the SIP timer A (T1 * 2) expires again, the called WVS server retransmits the SIP INVITE Request message to the called terminal B (806).

On the other hand, when the incoming WVS server confirms that the SIP timer CF1 is expired, and transmits a "SIP 181 Call is being forwarded" message to the calling network (807).

In addition, the incoming WVS server sends a call INPITE Request message in order to forward the corresponding call to the terminal (called terminal C) registered in the shaded call forwarding service of the called terminal B in advance at the same time as the process of "807". The call is sent to the called terminal C (808).

Then, the called terminal C transmits a SIP 180 (Ringing) Provisional Response message (callable message) to the called WVS server in response to the SIP INVITE Request message. (809).

Then, the destination WVS server transmits the SIP 180 (Ringing) Provisional Response (SIP 180) message (callable message) to the calling network (810).

Meanwhile, the called terminal C includes its media stream information in a call 200 response message and transmits it to the called WVS server (811).

Then, the called WVS server transmits the call connection response message (SIP 200 OK Response) to the calling network (812).

The incoming WVS server receives a SIP ACK Request message from the originating network in response to the SIP 200 OK Response message (813).

The called WVS server transmits the SIP ACK Request message to the called terminal C (814).

Accordingly, a WVS session is established between the originating terminal of the calling network and the called terminal C to make a call (815).

Meanwhile, upon successful completion of paging between the wireless access network 2 and the called terminal B according to the SIP INVITE Request message of the “804” process, the called terminal B reenters the wireless network and becomes active (active mode, 816). ) Accordingly, the called terminal B sends a SIP 180 (Ringing) Provisional Response message (callable message) in response to a SIP INVITE Request message sent from the calling network. Send to the destination WVS server (817). However, the SIP 180 (Ringing) Provisional Response (SIP 180) Ringing Provisional Response (SIP 180) Ringing Provisional Response (SIP 180) Ringing Provisional Response (SIP 180) Ringing Provisional Response (SIP 180) Ringing Provisional Response (SIP 180) Ringing Provisional Response (SIP 180) Ringing Provisional Response (SIP 180) Ringing Provisional Response (SIP 180) Ringing Provisional Response (SIP 180) Ringing Provisional Response (SIP 180) Ringing Provisional Response (SIP 180) ringing message is provided. ) Is ignored on the destination WVS server.

If the calling / receiving terminal is in the idle mode, it is necessary to enter the wireless network again to make a call. In other words, it must exit the idle state and become active. In this case, the originating terminal may transmit a SIP INVITE Request message to the called terminal after starting the idle state termination procedure first. However, the called terminal starts to switch to the active state after the call connection starts. In order for the called terminal to exit from the idle state, the wireless network (base station) must perform paging on the called terminal. This paging procedure can take a few seconds, because the terminal in idle state checks the wireless network only during PLI (Paging Listen Interval), and retry due to paging failure or multi-level paging in different paging groups. Because there is. Therefore, in order to prevent unwanted call forwarding or call dropping, the timer value for SIP INVITE transaction timeout should be set carefully.

Next, an example of a call connection processing procedure according to the present invention utilizing the state information of the terminal will be described with reference to FIGS. 9 and 10.

9 is another exemplary flowchart illustrating a call connection processing procedure when a called terminal is not in service in an mVoIP network according to the present invention.

In the state in which the terminating terminal B is SIP registered with the terminating WVS server (SIP server) 901, the network connection termination procedure may be performed because of leaving the service coverage without canceling the SIP registration or abnormal termination or unexpected restart of the base station. 902).

At this time, the destination WVS server receives a call connection request (SIP INVITE Request) message for connecting the call to the destination terminal B (903).

The called WVS server transmits a SIP 100 (Trying) Provisional Response (SIP 100) Provisional Response message to the originating network in response to the SIP INVITE Request message (904).

The destination WVS server requests a current state of the destination terminal B by transmitting a MS State Query Request message to a home AAA server (eg, an AAA authentication server) of the WiMAX network (905).

Then, the home AAA server transmits a MS State Query Response message to the destination WVS server in response to the MS State Query Request message to the destination WVS server (for example, NOT). -IN-SERVICE status) (906). Accordingly, the called WVS server confirms that the called terminal B is not currently in service (NOT-IN-SERVICE) and does not transmit a SIP INVITE Request message to the called terminal B anymore.

On the other hand, the called WVS server is subscribed to the shadow call forwarding service that is required to query all the incoming calls to the destination terminal C when the destination terminal B is in the unreceived state by querying the subscriber database (DB), etc. It is confirmed (907). At this time, the registered call forwarding telephone number (phone number of the called terminal C) is also obtained. If the called terminal B is not registered in the shadow call forwarding service, the called WVS server does not wait for the SIP INVITE transaction timeout and immediately returns an error message (for example, temporarily unavailable (SIP 480 Temporarily). The call can be terminated by sending an Unavailable message) to the calling network. The unreceivable state may be a loss on a network link, a network disconnection, coverage loss, power shutdown, or the like.

Meanwhile, the incoming WVS server confirming the subscription of the shadow forwarding service of the called terminal B transmits a "SIP 181 Call is being forwarded" message to the forwarding network (step 908).

The incoming WVS server simultaneously sends a call INPITE Request message to forward the corresponding call to the terminal (called terminal C) registered in the shadowed call forwarding service of the called terminal B in advance. The call is sent to the called terminal C (909).

Then, the called terminal C transmits a SIP 180 (Ringing) Provisional Response message (callable message) to the called WVS server in response to the SIP INVITE Request message. (910).

Then, the incoming WVS server transmits the SIP 180 (Ringing) Provisional Response (SIP 180) Provisional Response (message) message to the calling network (911).

Meanwhile, the called terminal C includes its media stream information in a call 200 response message and transmits it to the called WVS server (912).

Then, the called WVS server transmits the call connection response (SIP 200 OK Response) message to the calling network (913).

The incoming WVS server receives a SIP ACK Request message from the originating network in response to the SIP 200 OK Response message (914).

The called WVS server transmits the SIP ACK Request message to the called terminal C (915).

Accordingly, a WVS session is established between the originating terminal of the calling network and the called terminal C to make a call (916).

As described above, in the shadow forwarding service, when the mVoIP destination terminal is located in the shadow area, the wireless modem is in the idle state, the mVoIP destination terminal is turned off, or the call connection request message is displayed. If the mVoIP called terminal cannot receive the call, such as a delay, the shadow call forwarding service is activated so that the other phone number preset (registered) by the subscriber (other call access network number of the same terminal or another terminal) Call) to transfer the call to the call.

However, the above-mentioned shadow call forwarding service is available when the called terminal subscribed to the shadow call forwarding service in the mVoIP network is in a callable state but the response to the call connection request is delayed due to the current idle state. In addition, the caller does not hear the ring back tone (ringback tone or coloring) during the time delay in response to the call connection request, thereby terminating the call connection request.

Therefore, when a called terminal subscribed to a shadow call forwarding service is in a state where an incoming call is possible, such as an idle state or an IN-SERVICE state, there is a need for a method of preventing a shadow call forwarding and providing a ring back tone. . This will be described in detail with reference to FIG. 10 as follows.

10 is a flowchart illustrating another embodiment of a call connection processing procedure when a called terminal is in an idle mode according to the present invention.

First, the called terminal B subscribed to the shadow call forwarding service is in an idle mode (1001).

At this time, the incoming WVS server receives a call connection request (SIP INVITE Request) message for connecting the call to the called terminal B (terminal registered in the call forwarding service) from the calling network (1002).

The incoming WVS server transmits a SIP 100 (Trying) Provisional Response message to the originating network in response to the SIP INVITE Request message (1003).

The destination WVS server requests a current state of the destination terminal B by transmitting a MS State Query Request message to the home AAA server (eg, AAA authentication server) of the WiMAX network (1004).

Then, the home AAA server transmits a MS State Query Response message to the destination WVS server in response to the MS State Query Request message, such as an IDLE. Status) (1005).

Accordingly, the called WVS server confirms that the called terminal B is in the idle state and adjusts the SIP timer value for the SIP INVITE transaction timeout so as to have sufficient time for the paging to be completed (1006). Of course, there is a probability that the called terminal B, which is in the idle state, terminates the network connection at the point in time, so that paging fails.

The called WVS server transmits the SIP INVITE Request message to the called terminal B (1007) and drives the SIP timer A (T1 = 500ms). Then, the SIP INVITE Request message of the process “1007” triggers paging. That is, when the wireless access network 2 receives the SIP INVITE Request message of the “1007” process destined for the called terminal B, since the called terminal B is in the idle state 1001, the wireless access network 2 enters the wireless network again and becomes active ( Paging procedure is performed to return to the active mode.

On the other hand, the destination WVS server transmits a SIP 180 (Ringing) Provisional Response (SIP 180) Provisional Response message (callable message) on behalf of the destination terminal B (1008). Through the operation of the “1008” process, the caller can hear the ring back tone or coloring.

When the SIP timer A (T1 = 500ms, call connection request message retransmission timer) expires, the destination WVS server retransmits the SIP INVITE Request message to the destination terminal B (1009) and the SIP timer A (T1 *). 2) drive.

When the SIP timer A (T1 * 2) expires again, the destination WVS server retransmits the SIP INVITE Request message to the destination terminal B (1010) and drives the SIP timer A (T1 * 4).

When the SIP timer A (T1 * 4) expires again, the destination WVS server retransmits the SIP INVITE Request message to the destination terminal B (1011).

On the other hand, when the called terminal B completes the paging procedure and re-enters the network (ie, becomes active) (1012), the called WVS server responds to the SIP INVITE Request message by SIP 180 (ringing). A Provisional Response (SIP 180) Provisional Response (SIP 180) message (callable message) is received from the called terminal B (1013). However, since the called WVS server has already sent a SIP 180 (Ringing) Provisional Response message (callable message) to the calling network in the process of “1008” on behalf of the called terminal B, In step 1013, the SIP 180 (Ringing) Provisional Response message (callable message) actually received from the called terminal B is ignored.

Meanwhile, the called terminal B includes its media stream information in a call 200 response message and transmits it to the called WVS server (1014).

Then, the incoming WVS server transmits the call connection response message (SIP 200 OK Response) message to the calling network (1015).

The incoming WVS server receives a SIP ACK Request message from the originating network in response to the SIP 200 OK Response message (1016).

The destination WVS server transmits the SIP ACK Request message to the destination terminal B (1017).

Accordingly, a WVS session is established between the originating terminal and the called terminal B of the calling network to make a call (1018).

11 is a flowchart illustrating another embodiment of a method for preventing unnecessary call forwarding and providing a quick ring back tone in an mVoIP network according to the present invention.

First, when an incoming WiMAX VoIP Service (WVS) server (called call control server) receives a SIP INVITE Request message from a calling network directed to a called terminal B (a terminal registered with a call forwarding service) (1101) In operation 1102, the AAA (Authentication, Authorization, Accounting) server of the WiMAX network requests the current state of the called terminal B through a MS State Query Request message.

At this time, if the home AAA server (eg, AAA authentication server) does not have a terminal status reporting function, a response indicating that the terminal status reporting function is not supported through a MS State Query Response message is sent to the destination WVS server. To pass. On the other hand, if the home AAA server has a terminal status reporting function, the status of the called terminal B is "ACTIVE", "IDLE" state, "service" through the MS State Query Response message. Answer to the incoming WVS server that it is in the "IN-SERVICE" state, or "NOT-IN-SERVICE" state.

Accordingly, the receiving WVS server receiving the MS State Query Response message checks whether the home AAA server has a terminal state reporting function (1103).

As a result of the check (1103), if the home AAA server does not have a terminal status reporting function, the incoming WVS server processes the received INPITE Request message independently without interworking with the home AAA server (1104). As such, an example of a conventional call connection processing procedure in which state information of a terminal is not utilized is as described above with reference to FIGS. 7 and 8.

As a result of the check 1103, if the home AAA server has a terminal status reporting function, the status of the called terminal B is "ACTIVE" state, "IDLE" state, "IN-SERVICE" state. Check whether it is in the "NOT-IN-SERVICE" state (1105).

Here, the "ACTIVE" state means that the called terminal B is in an active mode and has at least one IP address for a WiMAX VoIP Service (WVS). In addition, the "IDLE" state means that the called terminal B is in an idle mode and has at least one IP address for WVS. The "IN-SERVICE" state means that the home AAA server has at least one IP address for the WVS although the home AAA server does not know whether the called terminal B is active or idle. And the "NOT-IN-SERVICE" state means that the home AAA server does not have a valid IP address for WVS for the called terminal B.

When the check result 1105 confirms that the called terminal B is in an "ACTIVE" state, the called WVS server sends a SIP response message from the called terminal B, that is, a SIP 180 (ringing) response (SIP 180 (Ringing). (Response) A message (callable message) is received and received (1106), and the call processing between the calling terminal and the called terminal B is performed according to a known conventional method (1107).

As a result of the check (1105), when the called terminal B confirms that it is in a "NOT-IN-SERVICE" state, the called WVS server drives the shaded call forwarding service (1108) and the calling terminal and the called terminal C (preliminary). In step 1109, call processing between the UEs registered in the shadow forwarding service is performed. That is, if the shadow call forwarding service is set for the corresponding subscriber and another available device is registered, the incoming WVS server transmits a SIP INVITE Request message to the other available device. Otherwise, the called WVS server responds with a SIP response message (eg, SIP 480 Temporarily Unavailable) that informs the calling terminal of its status (situation). As such, an example of a call connection processing procedure when the called terminal B is not serving in the network is as described above with reference to FIG. 9.

When the check result 1105 recognizes that the called terminal B is in the "idle" state or the "in-service" state, the called WVS server times out a call initiation request (SIP INVITE) transaction. Adjust the SIP timers associated with (ie, timer A and / or timer B shown in FIG. 7) to ensure sufficient time for paging to complete, and to send the SIP INVITE Request message. Transmitting to the destination terminal B (1110).

Thereafter, the destination WVS server directly receives the SIP 180 (ringing) message before receiving the SIP response message from the called terminal B, that is, the actual SIP 180 (ringing) provisional response message (callable message). In response to the Provisional Response (SIP 180 (Ringing) Provisional Response) message (callable message) to the calling terminal A (1111). In this case, the incoming WVS server may be implemented to transmit the SIP 180 (Ringing) Provisional Response (SIP 180) Provisional Response (SIP 180) message (callable message) only when the called terminal B is in the "idle" state. have. And if the called WVS server has already responded with a SIP 180 (Ringing) Provisional Response message (callable message), later the actual SIP 180 (ringing) Provisional Response from the called party B Even if the SIP 180 (Ringing) Provisional Response) message (callable message) is received, it is discarded without being delivered to the calling terminal A (1111).

The called WVS server proceeds with call processing between the calling terminal and the called terminal B (1112).

Meanwhile, when the called WVS server does not receive any SIP response message from the called terminal B until the SIP timers expire, a SIP response message (for example, SIP 480 Temporarily Unavailable) indicating the status (situation) Message) to the calling terminal A. As such, an example of a call connection processing procedure when the called terminal B is in an idle mode has been described above with reference to FIG. 10.

On the other hand, in the mVoIP network according to the present invention as described above, the method for preventing unnecessary call forwarding and providing a quick ring back tone may be implemented in the form of program instructions that can be executed by various computer means and recorded in a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. The medium may be a transmission medium such as an optical or metal line, a wave guide, or the like, including a carrier wave for transmitting a signal designating a program command, a data structure, or the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Various permutations, modifications and variations are possible without departing from the spirit of the invention.

Therefore, the scope of the present invention should not be construed as being limited to the embodiments described, but should be determined by the scope of the appended claims, as well as the appended claims.

The present invention can be used in the mVoIP network to prevent a call forwarding when the called terminal is in the shaded call, and to prevent the termination of the call connection request of the calling subscriber due to the response delay.

Claims (20)

In the shadow forwarding method,
Receiving a call connection request message by the call control server, acquiring a current state of the called terminal and checking whether it is in a callable state;
Performing a shadow call forwarding service if the current state of the called terminal is incapable of receiving a call as a result of the checking of the state checking step; And
If the current state of the called terminal is a callable state as a result of the checking of the state, the call control server requests the connection of the incoming call after preventing the incoming call from being shadowed.
Shading forward prevention method comprising a.
The method of claim 1,
As a result of the checking of the state, if the current state of the called terminal is a callable state, the call control server delivers a first call available message in response to the call connection request message on behalf of the called terminal, thereby making a call. To provide ring back tone to
Shade forwarding prevention method further comprising a.
The method of claim 2,
Discarding, by the call control server, the second call available message received through the called CSCF from the called terminal;
Shade forwarding prevention method further comprising a.
The method of claim 1,
The status check step,
And the call control server checks whether a current state of the called terminal is in an idle state, an awake state, or not connected.
The method of claim 4, wherein
The status check step,
And the call control server acquires whether the current state of the called terminal is in an awake state, an idle state, or not connected in association with a system that knows the current state of the terminal.
In the method for providing a ring back tone,
Receiving a call connection request message by the call control server, acquiring a current state of the called terminal and checking whether it is in a callable state;
Performing a shadow call forwarding service if the current state of the called terminal is incapable of receiving a call as a result of the checking of the state checking step; And
As a result of the checking of the state, if the current state of the called terminal is a callable state, the call control server delivers a first call available message in response to the call connection request message on behalf of the called terminal, thereby making a call. To provide ring back tone to
Method for providing a ring-tone sound comprising a.
The method according to claim 6,
Discarding, by the call control server, the second call available message received through the called CSCF from the called terminal;
The method for providing a ring tone further comprising a.
The method according to claim 6,
The status check step,
And the call control server checks whether the current state of the called terminal is in an idle state, an awake state, or not connected.
The method of claim 8,
The status check step,
And the call control server acquires whether the current state of the called terminal is an awake state, an idle state, or an unconnected state by interworking with a system that knows the current state of the terminal.
In the shadow forwarding method,
Receiving a call connection request message by the call control server, acquiring and confirming a current state of the called terminal;
If the current state of the called terminal is an ACTIVE state as a result of the checking of the state checking step, processing the incoming call;
Performing a corresponding call termination or shadow forwarding service when the current state of the called terminal is not in service (NOT-IN-SERVICE) as a result of the checking of the state checking step; And
As a result of the checking of the state, if the current state of the called terminal is an idle state or an IN-SERVICE state, the call control server adjusts a call connection request transaction timeout so that the incoming call is shaded. Handling the incoming call after preventing it from being diverted
Shading forward prevention method comprising a.
The method of claim 10,
As a result of the checking of the state, if the current state of the called terminal is in the idle state, the call control server delivers a first call available message in response to the call connection request message on behalf of the called terminal. Making a ring back tone to the calling terminal
Shade forwarding prevention method further comprising a.
The method of claim 11,
Discarding, by the call control server, the second call available message received from the called terminal;
Shade forwarding prevention method further comprising a. The method of claim 12,
If the current status of the called terminal is IN-SERVICE, the call control server may make the first call in response to the call connection request message on behalf of the called terminal. Delivering a message to provide a ring back tone to the calling terminal;
Shade forwarding prevention method further comprising a.
The method of claim 10,
The status check step,
The call control server interoperates with a home AAA (Authentication, Authorization, Accounting) server that knows the current state of the terminal to determine whether the current state of the called terminal is active, idle, or in service. How to prevent shadow forwarding to obtain whether it is in (IN-SERVICE) state or not-in-service state.
The method of claim 14,
The status check step,
When the call control server receives a call connection request message, requesting a current state of the called terminal to the home AAA server; And
If the call control server does not have a terminal status report function in the home AAA server, the call connection request message received thereafter is independently processed without interworking with the home AAA server, and if the home AAA server has a terminal status report function, Acquiring whether a current state of the called terminal is an active state, an idle state, an in-service state, or a non-in-service state;
Shading forward prevention method comprising a.
The method of claim 10,
Adjusting the call connection request transaction timeout,
And adjusting a timer to secure a time at which paging for the called terminal can be completed.
17. The method of claim 16,
If the call control server does not receive any response message from the called terminal until the timer expires, the call control server transmits a temporary call unavailable message indicating the current state to the calling terminal
Shade forwarding prevention method further comprising a.
In the method for providing a ring back tone,
Receiving a call connection request message by the call control server, acquiring and confirming a current state of the called terminal;
If the current state of the called terminal is an ACTIVE state as a result of the checking of the state checking step, processing the incoming call;
Performing a corresponding call termination or shadow forwarding service when the current state of the called terminal is not in service (NOT-IN-SERVICE) as a result of the checking of the state checking step; And
As a result of the checking of the state, if the current state of the called terminal is in the idle state, the call control server delivers a first call available message in response to the call connection request message on behalf of the called terminal. Making a ring back tone to the calling terminal
Method for providing a ring-tone sound comprising a.
The method of claim 18,
Discarding, by the call control server, the second call available message received from the called terminal;
The method for providing a ring tone further comprising a.
The method of claim 19,
If the current status of the called terminal is IN-SERVICE, the call control server may make the first call in response to the call connection request message on behalf of the called terminal. Delivering a message to provide a ring back tone to the calling terminal;
The method for providing a ring tone further comprising a.

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