Wireless communication system for performing combined service between terminals having different communication environments

Abstract

A method for transmitting information in a wireless communication system and a wireless communication terminal supporting the method, are discussed. In one embodiment, when an application server sends to a receiving terminal a specific message for checking radio environment information or a message including a radio environment capability, the receiving terminal having received the message may send a response message with its own radio environment information to the application server, such that the radio environment information related to the receiving terminal can be sent to the sending terminal after analyzed by the application server.

Claims

1. A method by a Combined Circuit-Switched and Internet protocol Multimedia Subsystem (CSI) Application Server (AS) for supporting a CSI session between an Internet protocol Multimedia Subsystem (IMS) User Equipment (UE) and a CSI UE, the method comprising: generating, by the CSI AS, a first message including information about IMS registration status of the IMS UE and information about radio environment capability of the IMS UE, wherein the radio environment capability indicates whether circuit-switched and packet-switched services are simultaneously supported; sending, by the CSI AS, the first message to the CSI UE in a Circuit-Switched (CS) domain; and sending, by the CSI AS, a response message to the IMS UE.

2. The method of claim 1, wherein the CSI AS exchanges capability information with the CSI UE on behalf of the IMS UE.

3. The method of claim 1, wherein the IMS UE supports communications over only a Packet-Switched (PS) domain, and wherein the CSI UE supports communications over both the CS domain and the PS domain.

4. The method of claim 1, wherein capability information of the IMS UE is included in a header of the first message.

5. The method of claim 1, the method further comprising: receiving, by the CSI AS from the CSI UE, a second message including capability information of the CSI UE in response to the first message.

6. The method of claim 1, wherein the first message is a Session Initiation Protocol (SIP) based INVITE message.

7. The method of claim 5, wherein the capability information of the CSI UE includes at least one of a Multiple Radio Access Bearer/Dual Transfer Mode (MultiRAB/DTM), predetermined IMS service information, or capability version information of the CSI UE.

8. The method of claim 1, further comprising: receiving, by the CSI AS, a request message from the IMS UE, wherein the request message is for an initial setup of a session including both a voice component on the CS domain and a non-voice component on a Packet-Switched (PS) domain.

9. The method of claim 8, wherein the CSI AS performs a session splitting by sending the voice component to the CS domain and sending the non-voice component to the PS domain.

10. The method of claim 1, wherein the first message is sent via a Media Gateway Control Function (MGCF).

11. The method of claim 10, wherein the first message is converted into an ISUP (ISDN (Integrated Services for Digital Network) User Part) message by the MGCF and the converted ISUP message is forwarded to the CSI UE.

12. The method of claim 1, wherein the first message further includes a capability version.

13. A method by a Combined Circuit-Switched and Internet protocol Multimedia Subsystem (CSI) User Equipment (UE) for communicating over a CSI session between an Internet protocol Multimedia Subsystem (IMS) UE and the CSI UE, the method comprising: receiving, by the CSI UE from a CSI Application Server (AS), a first message in a Circuit-Switched (CS) domain, wherein the first message including information about IMS registration status of the IMS UE and information about radio environment capability of the IMS UE is generated by the CSI AS when the CSI AS receives a request message from the IMS UE, wherein capability information of the IMS UE is added to the first message by the CSI AS, and wherein the radio environment capability indicates whether circuit-switched and packet-switched services are simultaneously supported; and sending, by the CSI UE to the CSI AS, a second message including capability information of the CSI UE in response to the first message.

14. The method of claim 13, wherein the capability information further includes a capability version.

15. A Combined Circuit-Switched and Internet protocol Multimedia Subsystem (CSI) Application Server (AS) for supporting a CSI session between an Internet protocol Multimedia Subsystem (IMS) User Equipment (UE) and a CSI UE, the CSI AS comprising: a transceiver; and a processor configured to: generate a first message including information about IMS registration status of the IMS UE and information about radio environment capability of the IMS UE, wherein the radio environment capability indicates whether circuit-switched and packet-switched services are simultaneously supported, control the transceiver to send the first message to the CSI UE in a Circuit-Switched (CS) domain, and control the transceiver to send a response message to the IMS UE.

16. The CSI AS of claim 15, wherein the first message further includes a capability version.

17. A Combined Circuit-Switched and Internet protocol Multimedia Subsystem (CSI) User Equipment (UE) for communicating over a CSI session between an Internet protocol Multimedia Subsystem (IMS) UE and the CSI UE, the CSI UE comprising: a transceiver; and a processor configured to: control the transceiver to receive, from a CSI Application Server (AS), a first message in a Circuit-Switched (CS) domain, wherein the first message including information about IMS registration status of the IMS UE and information about radio environment capability of the IMS UE is generated by the CSI AS when the CSI AS receives a request message from the IMS UE, wherein capability information of the IMS UE is added to the first message by the CSI AS, and wherein the radio environment capability indicates whether circuit-switched and packet-switched services are simultaneously supported, and control the transceiver to send, to the CSI AS, a second message including capability information of the CSI UE in response to the first message.

18. The CSI UE of claim 17, wherein the capability information further includes a capability version.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a conceptual view illustrating a basic session setup between CSI UEs.

(2) FIG. 2 is a view illustrating a radio environment information exchange procedure between CSI UEs upon establishing a CS call.

(3) FIG. 3 is a signal flowchart illustrating a process for setting call and session between different types of terminals.

(4) FIG. 4 is a signal flowchart illustrating a first embodiment of a method for transmitting multimedia information in a wireless communication system according to the present invention.

(5) FIG. 5 is a signal flowchart illustrating a second embodiment of a method for transmitting multimedia information in a wireless communication system according to the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(6) Hereinafter, exemplary embodiments of this disclosure will be explained in detail as follows.

(7) In general, different types of terminals (e.g., CS UE, CSI UE and IMS UE) have different communication environments. Supportable services may depend on various environments, or constraints on communications may be generated according to the various environments.

(8) For example, a CSI UE simultaneously supports Circuit-Switched (CS) service and Packet-Switched (PS) service only under the coverage of a MultiRAB/DTM. The IMS UE can establish and control several sessions and bearers under a packet-based environment, but may use different services based upon a user's service registration. In addition, supportable services may be varied according to radio interfaces supporting communications and construction of a core network. Types of usable services may be restricted according to with whom the communication is performed.

(9) Recently, when a communication is connected between end terminals (e.g., an originating terminal and a terminating terminal), information related to the connected communication can only be known. However, besides the information of the connected communication, such additional information as information related to a radio environment which the terminating terminal expose to, information with respect to which terminal the terminating terminal is now communicating with, and the like, are not exchanged between the terminals for the communication. Accordingly, which services can additionally be used may not be recognized.

(10) Therefore, this disclosure proposes a method for allowing a combined service to be smoothly performed by exchanging information between two terminals after an initial communication (e.g., voice communication or multimedia communication) is connected among various or different types of terminals. That is, this disclosure proposes a method for exchanging information between CSI UE and IMS UE, in order to support communications for one or more components (e.g., voice component or non-voice multimedia component) between the CSI UE and the IMS UE.

(11) Here, information exchanged between the two terminals (i.e., CSI UE and IMS UE) may be described as follows. IMS registration information Radio environment information such as MultiRAB/DTM Information on available services CS Registration information User preference service information Information related to other usable services

(12) These pieces of information can be exchanged by the following signaling after an initial communication is set. CS signaling PS signaling (including IMS) Mutual mapping signaling in case of CS/PS interworking

(13) Therefore, in this disclosure, the aforementioned information can be provided according to various network environments or according to counterpart UEs as follows.

(14) 1. Communication between IMS UE and CS UE Multimedia capability supportable by CS UE Radio environment information on CS UE Capability information such as MultiRAB/DTM supportable CS UE Registration status information on IMS UE Usable service list of IMS UE IMS UE capability information IMS UE capability version information

(15) 2. Communication between IMS UE and CSI UE Registration status information on IMS UE usable service list of IMS UE IMS UE capability information IMS UE capability version information IMS UE notification information CSI UE capability version information Radio environment information on CSI UE IMS registration status information on CSI UE CSI UE capability information Usable service list of CSI UE CSI capable notification CS status information on CSI UE

(16) 3. Communication between IMS UE and IMS UE Usable IMS service information Preference service information on counterpart UE Capability version information

(17) Here, CSI AS, MGCF and the like may exist between the IMS UE and the CSI UE to thus allow a smooth communication between the IMS UE and the CSI UE. In addition, upon the interworking between the signaling in an IMS domain (i.e., SIP) and the signaling in a CS domain (i.e., ISUP), the aforementioned information may be included and exchanged. Therefore, a contents for a related header or body should be added to the IMS regarding the aforementioned information. Also, a parameter of an ISUP message which can be mapped to the SIP should be newly defined or an existing parameter thereof should be able to be used. When using this method, an IMS registration state of a counterpart UE, current radio environment and capability, a supportable capability and capability version and other available services can be recognized based upon information exchanged in a state of VoIP or typical multimedia being set.

(18) That is, upon a VoIP connection, a communication on the CS domain may be performed by a PSTN interworking. Accordingly, the CSI UE can only use a simple voice service without any information as to whether another UE is a CS UE or an IMS UE. If the counterpart UE is either a CSI UE or an IMS UE, the CSI UE can additionally use a multimedia service while using the voice service. In spite of that, however, the CSI UE may not even attempt to perform any communication for any service due to the lack of such information. Also, since the IMS UE cannot recognize whether its counterpart UE is CSI UE, CS UE or IMS UE, the IMS UE may not perform an additional communication. Even if any communication is additionally attempted, the attempt may be made without exact radio environment information related to the counterpart UE, resulting in a much more increase in probability of communication failure.

(19) Therefore, this disclosure may allow in a communication between an IMS UE and a CSI UE that they can exchange and use various usable information upon their initial communication by adding an interworking function and a mapping function.

(20) Methods for transmitting multimedia information in a wireless communication system according to the present invention may be classified according to upon setting (establishing) an IMS service session and upon setting a CS call.

(21) First, a method for transmitting information in a wireless communication system upon setting an IMS service session may denote a method in which when an IMS UE sends a session setup INVITE message, a CSI AS may recognize information related to a CSI UE to inform to the IMS UE, which is performed by the following two schemes.

(22) According to a first scheme, the CSI AS may recognize radio environment information related to the CSI UE by converting a SIP message into an ISUP message, and thereafter may inform the IMS UE of the recognized radio environment information on the CSI UE. The radio environment information may be included in a header or body of a SIP message which is sent from the CSI AS to PS and CS domains of the CSI UE.

(23) In the first scheme, the CSI AS converts (maps, changes, etc.) a SIP request received from the IMS UE and then includes radio environment information related to SIP capability in the converted SIP request. The CSI AS may forward the information included SIP request to the CSI UE. Here, the SIP request (message) may be sent by being converted into an ISUP message used in a PSTN (or vice-versa).

(24) If the radio environment information is included in the ISUP message, the CSI UE may include its radio environment information in the ISUP message for response. The ISUP message may be re-converted into the SIP response message by a SIP-ISUP mapping, to be sent to the CSI AS. Therefore, the CSI AS may analyze the received SIP response message, and then may send the IMS UE the radio environment information related to the CSI UE in a manner of sending a warning message, or the like.

(25) According to a second scheme, the CSI AS may recognize radio environment information related to the CSI UE by exchanging OPTIONS between the CSI AS and the CSI UE, so as to inform the IMS UE of the recognized radio environment information on the CSI UE.

(26) In the second scheme, the CSI AS may send a separate OPTIONS request to the CSI UE in order to recognize the radio environment information related to the CSI UE. The CSI UE may forward its capability and radio environment information to the CSI AS in response to the OPTIONS request. The CSI AS then may analyze the response message received from the CSI UE, to thereby forward the radio environment information related to the CSI UE to the IMS UE in the manner of using a warning message, or the like.

(27) A method for transmitting information in a wireless communication system upon setting a CS call may be a method in which a CSI UE includes its own information in a SETUP message or an INVITE message to inform to an IMS UE.

(28) Preferably, the SETUP message may be sent when the CSI UE has set a voice communication at the beginning, while the INVITE message (or OPTIONS message) may be sent when the CSI UE has set a multimedia communication at the beginning.

(29) Preferably, the sent information may include CSI UE related radio environment information (e.g., MultiRAB/DTM cell, GPRS network, UTRAN network, etc.), CSI UE related capability information (e.g., information as to whether only GPRS can support, only CS can support, DTM can support, or MultiRAB/DTM can support), CSI UE related IMS registration information, available service list of CSI UE (e.g., PoC, a service list of video calls, etc.), CSI capable notification (i.e., information as to whether a current terminal may be a CSI capable terminal), capability version information, and the like.

(30) FIG. 4 illustrates a first embodiment of a method for transmitting multimedia information in a wireless communication system according to the present invention, which illustrates a method for recognizing a radio environment of a CSI UE by converting (mapping, changing, etc.) a SIP message into an ISUP message when setting an IMS service session.

(31) As illustrated in FIG. 4, an IMS UE may send an INVITE message to a S-CSCF2 of an IMS core to which the IMS UE belongs, thereby requesting a session setup for connecting a SIP-based voice service with a CSI UE (i.e., terminating UE) (S40). The S-CSCF2 may forward the INVITE message to a S-CSCF1 of the IMS core to which the CSI UE belongs according to an IMS session setup procedure (S41).

(32) After receiving the INVITE message, the S-CSCF1 may perform a service logic to authenticate the CSI UE (i.e., the terminating UE) (S42), and then may forward the INVITE message to the CSI AS with reference to routing information read from a HSS (not shown) (S43).

(33) The CSI AS having received the INVITE message either may split or forward a session according to a media type included in the INVITE message. For example, if the INVITE message includes a voice component and a non-voice multimedia component, the CSI AS may perform a session split such that the CSI AS sends the voice component to a CS domain of the CSI UE and sends the non-voice multimedia component to an IMS domain.

(34) On the other hand, if the INVITE message includes any one of the voice component and the non-voice multimedia component, the CSI AS may send the voice component to the CS domain of the CSI UE or may send the non-voice multimedia component to the IMS domain. Here, the CSI AS may add a radio environment related header to the INVITE message (i.e., a SIP message) and may send the header-added message to the CS and/or IMS domain(s). This is because a radio environment field should be included in a request message in order for the CSI UE to add its radio environment information to a response message. FIG. 4 illustrates an example in which the INVITE message only includes the voice component. Accordingly, the CSI AS may determine that the radio environment related header is added to the INVITE message including the voice component, to be then sent to the CS domain of the CSI UE.

(35) The CSI UE can simultaneously perform CS and PS services under the coverage of a MultiRAB/DTM. Accordingly, in order to perform communication for additional multimedia data, the CSI UE should be under the coverage of the MultiRAB/DTM, and such environment-related information should be forwarded to the IMS UE. However, the CSI UE may forward its radio environment via a UUS of a CS SETUP signaling when a received SETUP message includes the corresponding radio environment information.

(36) Accordingly, in one embodiment, for receiving the radio environment information from the CSI UE, the CSI AS may add the radio environment header to the INVITE message, and then may send the header added INVITE message to the CS domain. The following [Table 1] shows an exemplary INVITE message to be forwarded to the CS domain by the CSI AS.

(37) TABLE-US-00001 TABLE 1 SIP/2.0 200 OK Via: SIP/2.0/UDP pcscf2.visited2.net:5088;comp=sigcomp;branch=z9hG4bK361k21.1, SIP/2.0/UDP scscf2.home2.net;branch=z9hG4bK764z87.1, SIP/2.0/UDP icscf2_s.home2.net;branch=z9hG4bK871y12.1, SIP/2.0/UDP scscf1.home1.net;branch=z9hG4bK332b23.1, SIP/2.0/UDP pcscf1.visited1.net;branch=z9hG4bK240f34.1, SIP/2.0/UDP [5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp;branch=z9hG4bKnashds7 Record-Route: <sip:pcscf2.visited2.net:5088;lr;comp=sigcomp>>, <sip:scscf2.home2.net;lr>, <sip:scscf1.home1.net;lr>, <sip:pcscf1.visited1.net;lr> Privacy: none P-Access-Network-Info: 3GPP-UTRAN-TDD; utran-cell-id-3gpp=234151D0FCE11 From: <sip:user1_public1@home1.net>; tag=171828 To: <tel:+12125552222>;tag=314159 Call-ID: cb03a0s09a2sdfglkj490333 Cseq: 127 INVITE Contact: <sip:[5555::eee:fff:aaa:bbb]:8805;comp=sigcomp>;+g.3gpp.cs- voice Allow: INVITE, ACK, CANCEL, BYE, PRACK, UPDATE, REFER, MESSAGE, OPTIONS Server: PMI-0EA2, Radio-Environment : capability of IMS UE Content-Type: application/sdp Content-Length: (...) v=0 o= 2987933615 2987933617 IN IP6 5555:: eee:fff:aaa:bbb s= c=IN IP6 5555::eee:fff:aaa:bbb t= 0 0 m=voice 3402 TCP/MSRP * a=accept-types:text/plain text/html message/cpim a=path:msrp://[5555::eee:fff:aaa:bbb]:3402/s234167;tcp a=max-size:65536

(38) For example, the radio environment header indicates capability of the IMS UE, and may be set to CUV-001 or CUV-000. The CUV-001 may indicate that the CSI UE is under the coverage of the MultiRAB/DTM (i.e., simultaneously supporting PS and CS), and the CUV-000 may indicate that the CSI UE is not under the coverage of the MultiRAB/DTM (i.e., optionally supporting PS or CS).

(39) The INVITE message sent by the CSI AS may be forwarded to a MGCF via a S-CSCF1 in order to be changed (converted) into a protocol of the CS domain (S45 and S46). The MGCF may map the received INVITE message (i.e., SIP message) into an ISUP IAM message of the CS domain (S47). During this process, each header of the INVITE message is changed (converted) into a parameter of the ISUP IAM message. The following [Table 2] may show an example of the mapping between the INVITE message and the ISUP IAM message.

(40) TABLE-US-00002 TABLE 2 ISUP parameters SIP header Accept transport SIP URL Automatic congestion No parameter but suggested to extend SIP by level allowing a warning header Call reference Calll-ID Called party number To Calling party number From

(41) In another embodiment, the CSI AS may include UUS signaling information in a SIP body within the INVITE message. The CSI AS also may include indication information, which indicates the inclusion of the UUS signaling information in the SIP body, into a SIP header. The CSI AS accordingly may send the INVITE message including the UUS signaling information and the indication information to a MGCF/MGW. The MGCF/MGW may convert the received INVITE message into an ISUP message. Here, the UUS signaling information included in the INVITE message may be sent by being included in the ISUP message.

(42) The MGCF may send the converted ISUP IAM message to a CS MGW (S48). The CS MGW then may convert the ISUP IAM message into a SETUP message to send to the CSI UE (S49).

(43) Accordingly, the CSI UE may check whether the received SETUP message includes a radio environment capability. If the SETUP message includes the radio environment capability according to the checked result, the CSI UE may include its current radio environment information in a response message (i.e., a CONNECT message) to send to the CS MGW (S50). Here, in the UUS signaling, since contents for the radio environment is included in the SETUP message, the CSI UE may include its radio environment information in the CONNECT message to send to the CS MGW.

(44) The CS MGW may convert the received CONNECT message into the ISUP CON message to sent to a MGCF of the IMS core (S51). The MGCF then may convert the ISUP CON message into a SIP message (S52). The MGCF may send a 200 OK response message with respect to a voice service to the S-CSCF1 (S53). Here, if the ISUP CON message includes radio environment information, the MGCF may map the corresponding information to be suitable for formats defined in [Table 1] and [Table 2].

(45) The S-CSCF1 may forward the received 200 OK response message with respect to the voice service to the CSI AS (S54). The CSI AS may analyze the received 200 OK response message to recognize whether the radio environment of the CSI UE is a MultiRAB/DTM environment, thereby informing the IMS UE of the recognized information. For example, if the radio environment of the CSI UE is not the MultiRAB/DTM environment, the CSI AS may modify the 200 OK response message using a warning message or other appropriate response message code. If the warning message is used, the CSI AS may inform the IMS UE using the warning message that the CSI UE cannot simultaneously perform one or more services because it is not under the MultiRAB/DTM environment.

(46) The CSI AS may send the 200 OK response message to the S-CSCF1, with including the warning message or without including the warning message, according to the radio environment of the CSI UE (S56). The S-CSCF1 may forward the 200 OK response message to the S-CSCF2 according to the existing IMS procedure. The S-CSCF2 accordingly may forward the received 200 OK response message to the IMS UE (S57 and S58).

(47) Therefore, if the 200 OK response message does not have the warning message, the IMS UE may consider it as the CSI UE is under the MultiRAB/DTM environment, and accordingly may additionally perform a procedure for initiating a multimedia session (i.e. a process of adding a non-voice multimedia component) (S59 and S60). If the 200 OK response message has the warning message, on the other hand, the IMS UE does not additionally perform the procedure for initiating the multimedia session under a state of the voice service being connected.

(48) FIG. 5 illustrates a second embodiment of a method for transmitting multimedia information in a wireless communication system according to the present invention, which illustrates a method for recognizing a radio environment of a CSI UE via OPTIONS messages upon setting an IMS service session.

(49) As illustrated in FIG. 5, an IMS UE may send an INVITE message to a S-CSCF2 of an IMS core to which the IMS UE belongs, thereby requesting a session setup for connecting a SIP-based voice service with a CSI UE (i.e., terminating UE) (S70). The S-CSCF2 may forward the INVITE message to a S-CSCF1 of the IMS core to which the CSI UE belongs according to an IMS session setup procedure (S71).

(50) After receiving the INVITE message, the S-CSCF1 may perform a service logic to authenticate the CSI UE (i.e., the terminating UE) (S72), and then may forward the INVITE message to the CSI AS with reference to routing information read from a HSS (not shown) (S73).

(51) After receiving the INVITE message, the CSI AS may forward the corresponding INVITE message to a CS domain (S74S76), and simultaneously may send an OPTIONS request to an IMS domain of the CSI UE, thereby receiving CSI UE capability (S77).

(52) That is, the CSI AS may forward the INVITE message to the MGCF via the S-CSCF1, and then may send an OPTIONS request message to the S-CSCF1 so as to receive the current capability of the CSI UE as shown in the following [Table 3].

(53) TABLE-US-00003 TABLE 3 OPTIONS tel:+12125552222 SIP/2.0 Via: SIP/2.0/UDP [5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp;branch= z9hG4bKnashds7 Max-Forwards: 70 Route: <sip:pcscf1.visited1.net:7531;lr;comp=sigcomp>,<sip:orig@scscf1.- home1.net;lr> P-Preferred-Identity: <tel:+1-212-555-1111> P-Access-Network-Info: 3GPP-UTRAN-TDD; utran-cell-id- 3gpp=234151D0FCE11 Privacy: none From: <sip:user1_public1@home1.net>; tag=171828 To: <tel:+12125552222> Call-ID: cb03a0s09a2sdfglkj490333 Cseq: 127 OPTIONS Require: sec-agree Proxy-Require: sec-agree Security-Verify: ipsec-3gpp; q=0.1; alg=hmac-sha-1-96; spi-c=98765432; spi-s=87654321; port-c=8642; port-s=7531 Contact: <sip:[5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp> Accept-Contact: *,+g.3gpp.cs-voice,+g.3gpp.cs-video;explicit Allow: INVITE, ACK, CANCEL, BYE, PRACK, UPDATE, REFER, MESSAGE, OPTIONS Accept: application/sdp User-Agent: PMI-0007, REI-01 Content-Length: 0

(54) The S-CSCF1 may forward the received OPTIONS request to the CSI UE (S78). The CSI UE then may send to the S-CSC1 a response message (i.e., 200 OK message) with its capability (i.e., radio environment information) with respect to the OPTIONS request (S79). Here, the CSI UE may set its radio environment information to REI-01 or REI-00. The REI-01 may indicate that the CSI UE is under the coverage of the MultiRAB/DTM (i.e., simultaneously supporting PS and CS), while the REI-00 indicates that the CSI UE is not under the coverage of the MultiRAB/DTM (i.e. optionally supporting PS or CS). Also, the information may be forwarded by being added to a header or body of the request or response message.

(55) The following [Table 4] may show a structure of a 200 OK message with respect to the OPTIONS request.

(56) TABLE-US-00004 TABLE 4 SIP/2.0 200 OK Via: SIP/2.0/UDP pcscf2.visited2.net:5088;comp=sigcomp;branch= z9hG4bK361k21.1, SIP/2.0/UDP scscf2.home2.net;branch=z9hG4bK764z87.1, SIP/2.0/UDP icscf2_s.home2.net;branch=z9hG4bK871y12.1, SIP/2.0/UDP scscf1.home1.net;branch=z9hG4bK332b23.1, SIP/2.0/UDP pcscf1.visited1.net;branch=z9hG4bK240f34.1, SIP/2.0/UDP [5555::aaa:bbb:ccc:ddd]:1357;comp=sigcomp;branch= z9hG4bKnashds7 Record-Route: <sip:pcscf2.visited2.net:5088;lr;comp=sigcomp>>, <sip:scscf2.home2.net;lr>, <sip:scscf1.home1.net;lr>, <sip:pcscf1.visited1.net;lr> Privacy: none P-Access-Network-Info: 3GPP-UTRAN-TDD; utran-cell-id-3gpp=123451D0FCE11 From: <sip:user1_public1@home1.net>; tag=171828 To: <sip:user2_public1@home2.net>;tag=314159 Call-ID: cb03a0s09a2sdfglkj490333 Cseq: 127 OPTIONS Contact: <sip:user2_public1@home2.net >;+g.3gpp.cs-voice, <tel:+12125552222> Allow: INVITE, ACK, CANCEL, BYE, PRACK, UPDATE, REFER, MESSAGE, OPTIONS Server: PMI-0EA2, REI-01 Content-Type: application/sdp Content-Length: (...) v=0 o= 2987933615 2987933617 IN IP6 5555:: eee:fff:aaa:bbb s= c=IN IP6 5555::eee:fff:aaa:bbb t=0 0 m=message 0 TCP/MSRP * a=accept-types:text/plain text/html message/cpim image/ jpeg image/gif video/3gpp a=max-size:65536 m=video 0 RTP/AVP 96 a=rtpmap:96 H263-2000/90000 m=audio 0 RTP/AVP 97 a=rtpmap:97 AMR/8000

(57) The S-CSCF1 may forward the received 200 OK message to the CSI AS (S80). Here, the CSI AS is currently waiting for the response with respect to an actually requested session. If the response with respect to the actually requested session arrives, the CSI AS may configure radio environment information related to the CSI UE and a 200 OK with respect to the actually requested session.

(58) That is, the MGCF may convert the INVITE message received from the S-CSCF1 into an ISUP IAM message of the CS domain (S81). During this process, each header of the INVITE message may be changed (converts) into a parameter of the ISUP IAM message as shown in [Table 1]. The ISUP IAM message converted by the MGCF may be sent to the CS MGW (S82). The CS MGW then may convert the ISUP IAM message into a SETUP message, to send to the CSI UE (S83).

(59) The CSI UE may send a CONNECT message to the CS MGW in response to the received SETUP message (S84). The CS MGW may convert the received CONNECT message into an ISUP CON message, thereby sending the converted ISUP CON message to the MGCF of the IMS core (S85). The MGCF may recognize whether the CON message includes radio environment related parameter. If the CON message includes the radio environment related parameter, the MGCF may map the corresponding information into a header when converting the CON message into a SIP-based response message. Accordingly, the MGCF may map the received ISUP CON message into a SIP message (S86), and then sends a 200 OK response message to the S-CSCF1 with respect to a voice service (S87). The S-CSF1 then may forward the received 200 OK response message with respect to the voice service to the CSI AS (S88).

(60) Accordingly, the CSI AS may analyze both the 200 OK response message and the previously received 200 OK response message with respect to the OPTIONS request. The CSI AS then may recognize whether the radio environment of the CSI UE is the MultiRAB/DTM environment, thereby informing the IMS UE of the recognition. For example, if the radio environment of the CSI UE is not the MultiRAB/DTM environment, the CSI AS may modify the 200 OK message using a warning message or an appropriate response message code (S89).

(61) If the warning message is used, the CSI AS may inform the IMS UE by using the warning message that the CSI UE cannot simultaneously perform one or more services because the CSI UE is not under the MultiRAB/DTM environment.

(62) The CSI AS may send the 200 OK response message to the S-CSCF1, with including the warning message or without including the warning message, according to the radio environment of the CSI UE (S90). The S-CSCF1 may forward the 200 OK response message to the S-CSCF2 according to the existing IMS procedure. The S-CSCF2 accordingly may forward the received 200 OK response message to the IMS UE (S91 and S92).

(63) Therefore, if the 200 OK message does not have the warning message, the IMS UE may consider it as the CSI UE is under the MultiRAB/DTM environment, and accordingly may additionally perform a procedure for initiating a multimedia session (i.e. a process of adding a non-voice multimedia component) (S93 and S94). If the 200 OK response message has the warning message, on the other hand, the IMS UE may not additionally perform the procedure for initiating the multimedia session under a state of the voice service being connected.

(64) The method for exchanging radio environment information between the CSI AS and the CSI UE for a call request (i.e., INVITE message) with the CSI UE requested by the IMS UE may have been explained with reference to FIGS. 4 and 5 of the present invention. However, another embodiment of proceeding a call request with an IMS UE according to a request by a CSI UE may be applicable. Here, the functions of the CSI AS and the MGCF MGW are the same in both FIGS. 4 and 5, namely, the function of the CSI AS for exchanging radio environment information and the function of the MGCF/MGW are the same in FIGS. 4 and 5. Accordingly, the detailed description thereof will be omitted.

(65) As described above, this disclosure can effectively increase satisfaction of multimedia communications and support efficient communications, by forwarding radio environment information related to a CSI terminal to an IMS terminal and simultaneously providing information on further usable terminals between the two terminals.

(66) This disclosure has been explained with reference to the embodiments which are merely exemplary. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that this disclosure cover modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.