USOO8248453B2

(12) United States Patent (10) Patent No.: US 8.248,453 B2 Lee et al. (45) Date of Patent: Aug. 21, 2012

(54) CALL CONTROL SYSTEMAND METHOD (58) Field of Classification Search ...... 348/1401, FORMOBILE COMMUNICATION 348/1402, 14.03, 14.04-14.16; 379/201.01, 379/202.01; 370/260–271 (75) Inventors: Jong Phil Lee, Daegu (KR); Woo Jin See application file for complete search history. Ch. ang, Gumi-si (KR(KR) (56) References Cited (73) Assignee: Samsung Electronics Co., Ltd., Samsung-ro, Yeongton-gu, Suwon-si, U.S. PATENT DOCUMENTS Gyeonggi-do (KR) 7.359,373 B2 * 4/2008 Kuusinen et al...... 370,352 7,567,269 B2 * 7/2009 Sakano et al...... 348, 14.01 (*) Notice: Subject to any disclaimer, the term of this * cited by examiner patent is extended or adjusted under 35 U.S.C. 154(b) by 1341 days. Primary Examiner — Brian Ensey (74) Attorney, Agent, or Firm — Cha & Reiter, LLC (21) Appl. No.: 11/975,501 (57) ABSTRACT (22) Filed: Oct. 19, 2007 A call control system and method for mobile video telephony O O that enables an automatic call setup between a mobile video (65) Prior Publication Data telephony terminal and a mobile audio-dedicated terminal is US 2008/O1 OO692 A1 May 1, 2008 disclosed. A call control method for communication between mobile terminals having different capabilities includes (30) Foreign Application Priority Data receiving, at a called party terminal, a call setup message, transmitting a disconnection message to a calling party ter Oct. 31, 2006 (KR) ------10-2006-O106058 minal in response to the video call setup message and per forming a call setup procedure triggered by the called part (51) Int. Cl. terminal. H04N 7/4 (2006.01) (52) U.S. Cl...... 348/14.08: 348/14.01 25 Claims, 9 Drawing Sheets

TRANSMIT V CALL REQFROM MOBILE VIDEOTELEPHONY TERMINATO MOBILE COMMUNICATIONNETWORK

S102 TRANSMIT V CALL SETUP FROMMOBILE Y- COMMUNICATION NETWORK TO MOBILE AUDIO-DEDICATED TERMINAL SO X------WideO Cal 2

TRANSMIT DISCONNECT FROM MOBILE S104 AUDEO-DEDICATED TERMINAL TO MOBELE VIDEO TELEPHONY TERMINAL S108

SS Display Missiocau E STABLISH VOICE OR DATA S106. TRANSMIT ACALL REO FROM COMMUNICATIONLINK MOBILE AUDIO-DEDICATED TERMINATO MOBILE COMMUNICATIONNETWORK S107 TRANSMITA CALL SETUP FROM MOBILE COMMUNICATION NETWORK TO MOBILE WIDEOTELEPHONY TERMINAL

S109-- ESTABLISH VOICE COMMUNICATIONLINK U.S. Patent Aug. 21, 2012 Sheet 1 of 9 US 8.248,453 B2

U.S. Patent Aug. 21, 2012 Sheet 2 of 9 US 8.248,453 B2

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--|- U.S. Patent Aug. 21, 2012 Sheet 3 of 9 US 8.248,453 B2

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U.S. Patent Aug. 21, 2012 Sheet 4 of 9 US 8.248,453 B2 FIG. 4

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25ge/ U.S. Patent Aug. 21, 2012 Sheet 5 Of 9 US 8.248,453 B2

FIG. 5

S101 TRANSMIT V CALL REQFROM MOBILE VIDEOTELEPHONY TERMINAL TO MOBILE COMMUNICATION NETWORK

S102 TRANSMIT V CALL SETUP FROM MOBILE N- COMMUNICATION NETWORK TO MOBILE AUDIO-DEDICATED TERMINAL S103 N-- WideO Cal 2 NO

S104 TRANSMIT DESCONNECT FROM MOBILE AUDIO-DEDICATED TERMINAL TO MOBILE VIDEOTELEPHONY TERMINAL S105 S108 s DISPLAY"MISSEDCALL" ESTABLISHVOICE OR DATA S106 TRANSMIT ACALL REO FROM COMMUNICATIONLINK MOBILE AUDIO-DEDICATED TERMINAL TO MOBILE COMMUNICATIONNEWORK

S107 TRANSMITA CALL SETUP FROM MOBILE COMMUNICATION NETWORK TO MOBILE WIDEOTELEPHONY TERMINAL

S109 ESTABLISH VOICE COMMUNICATIONLINK U.S. Patent Aug. 21, 2012 Sheet 6 of 9 US 8.248,453 B2

008

U.S. Patent Aug. 21 , 2012 Sheet 7 Of 9 US 8.248,453 B2

dnT?9ST?OLITOU L'50|| XHUMAHN 00Z U.S. Patent Aug. 21, 2012 Sheet 8 of 9 US 8.248,453 B2

FIG. 8

TRANSMIT V CALL REOFROM S2O1 MOBILE WIDEOTELEPHONY TERMINAL TO MOBILE COMMUNICATION NETWORK TRANSMIT V CALL SETUPFROM S2O2 MOBILE COMMUNICATIONNETWORK TO MOBILE AUDIO-DEDICATED TERMINAL Videocal ad-NO S211 YES TRANSMITD NOT SEUPFROM ESTABLISHVOICE OR DATA S2O4 N-MOBILE VOICE DEDICATED TERMINAL TO COMMUNICATION CHANNEL MOBILE WIDEO TELEPHONY TERMINAL

S2O5

MOBILE WIDEO TELEPHONY TERMINAL RECEIVE NO A CALTRANST? S210

MOBILE WIDEO TELEPHONY MOBILE WIDEO TELEPHONY S2O6 TERMINAL GENERATEA CALL REQ TERMINAL GENERATE ALCALIREQ

TRANSMIT ACAL REOTO S2O7 MOBILE COMMUNICATIONNETWORK

TRANSMITA CALL SETUPFROM S208 MOBILE COMMUNICATION NETWORKTO MOBIE AUDIO-DEDICATED TERMINAL

S209 ESTABLISH VOICE COMMUNICATIONLINK U.S. Patent Aug. 21, 2012 Sheet 9 of 9 US 8.248,453 B2

008

00Z00|| US 8,248,453 B2 1. 2 CALL CONTROL SYSTEMAND METHOD an audio-dedicated terminal that does not support the audio FORMOBILE COMMUNICATION visual communication service.

CLAIM OF PRIORITY SUMMARY OF THE INVENTION This application claims, pursuant to 35 U.S.C. S 119(a), The present invention provides a call control system and priority to and the benefit of the earlier filing date of a Korean method for mobile communication that enable an automatic patent application entitled “CALL CONTROL SYSTEM call setup between mobile terminals having different capa AND METHOD FORMOBILE COMMUNICATION filed bilities. in the Korean Intellectual Property Office on Oct. 31, 2006 10 In accordance with an aspect of the present invention, a call and assigned Serial No. 2006-0106058, the contents of which control method for a communication between mobile termi are incorporated herein by reference. nals having different capabilities is disclosed. The call control method includes receiving, at a called party terminal, a call BACKGROUND OF THE INVENTION setup message, transmitting a disconnection message to a 15 calling party terminal in response to the video call setup 1. Field of the Invention message and performing a call setup procedure triggered by The present invention relates to mobile video telephony the called party terminal. and, in particular, to a call control system and method for In accordance with another aspect of the present invention, mobile video telephony that enable an automatic call setup a call control method for a mobile communication system between a mobile video telephony terminal and a mobile including a video telephony terminal, an audio-dedicated ter audio-dedicated terminal. minal, and a mobile communication network Supporting 2. Description of the Related Art communication between the terminals is disclosed. The call Video telephony is a service that enables participants to control method includes transmitting, at the video telephony communicate while viewing each other in real time. Video terminal, a video call request message to the mobile commu telephony can be implemented with a switch-based circuit 25 nication network, transmitting, at the mobile communication switching network or a packet switched All-IP network. network, a video call setup message to the audio-dedicated In order to implement video telephony over a mobile IP, terminal in response to the video call request message, trans H.323 and H.324M standards developed by the International mitting, at the audio-dedicated terminal, a disconnection Telecommunications Union (ITU) are recommended. message to the video telephony terminal through the mobile H.323 is a protocol designed to provide teleconferencing 30 communication network and transmitting, at the audio-dedi with Voice, video, and data capabilities on packet Switching cated terminal, an audio call request message to the mobile networks, and H.324 is a protocol for sharing voice, video and communication network. data over an analog telephone line. Meanwhile, H.324M In accordance with another aspect of the present invention, refers to a “mobile' extension of H.324 protocol developed a call control system for a mobile terminal is disclosed. The by the ITU. 35 call control system includes a radio frequency unit which H.324M uses H.261 and H.263 as video codecs and receives video call setup message, transmits a disconnection G.723.1 as an audio codec. H.261 is a digital video coding message in response to the video call setup message, and then standard designed for compressing and coding video data, transmits an audio call request message to a calling party and H263 and MPEG-4 are enhanced video codecs for com terminal, an audio processing unit for processing an audio pressed encoding for video conferencing. G.723.1 is an audio 40 signal generated during a communication session and a con codec providing 8Kbps codec bit rate. trol unit for controlling automatic transmission of the discon The Third Generation Partnership Project has adopted nection message and the audio call request message. H.324M as a standard for conversational video-telephony In accordance with another aspect of the present invention, over 3G, which is named 3G-324M. 3G-324M differs from a call control system includes an audio visual telephony ter H.324M in that it uses an Adaptive Multi-Rate (AMR) codec 45 minal that transmits a video call request message, an audio as the basic voice codec, and G.723.1 is optional. dedicated terminal that transmits a disconnection message to In addition, H.324 uses H.223 protocol for multiplexing the audio visual telephony terminal in response to the video Voice, video, and data; and H.245 protocol as a control pro call request message and a mobile communication network tocol for selecting a voice codec and assigning channels for a for Supporting communication between the audio visual tele point-to-point or a point-to-multipoint connection. 50 phony terminal and the audio-dedicated terminal. In the case of a video communication service using In accordance with another aspect of the present invention, H.324M, two terminals establish a call connection through a a call control method for a mobile terminal is disclosed. The call establishment procedure. Between the two terminals, an call control method includes transmitting a video call request audiovisual link is established. message, receiving an audiovisual communication unavail However, the conventional audiovisual communication 55 able message in response to the video call request message, service has a limitation in establishing a communication link and transmitting an audio call request message in response to between a video communication-enabled terminal and an the audiovisual communication unavailable message. audio-dedicated terminal. If a called party terminal does not In accordance with another aspect of the present invention Support the audiovisual communication function, a commu a call control method of a mobile communication system is nication channel cannot be established. In this case, the call 60 disclosed. The mobile communication system includes a ing party terminal receives a message informing the calling mobile communication network Supporting communication party that the called party terminal cannot respond to the between a video telephony terminal and an audio-dedicated audiovisual communication call. That is, the calling party terminal. The call control method includes transmitting, at the terminal does not know the capacity of the called party ter Video telephony terminal, video call request message to the minal before the call is initiated, and hence it periodically 65 mobile communication network, transmitting, at the mobile attempts audiovisual communication with the called party communication network, video call setup message to the terminal without recognizing that the called party terminal is audio-dedicated terminal in response to the video call request US 8,248,453 B2 3 4 message, transmitting, at the audio-dedicated terminal, a dis Smartphone, 3" generation standard mobile terminal, Code connection message to the video telephony terminal in Division Multiple Access (CDMA) terminal, Global System response to the video call setup message through the mobile for Mobile communication (GSM) terminal, Global Packet communication network, transmitting, at the video telephony Radio Services (GPRS) terminal, Wireless Local Area Net terminal, an audio call request message to the mobile com work (WLAN) terminal, Wireless Broadband (WiBro) Ter munication network and transmitting, at the mobile commu minal, and High Speed Downlink Packet Access (HSDPA) nication network, an audio call setup message to the audio terminal. dedicated terminal in response to the audio call request A mobile terminal Supporting the video telephony service message. is referred-to as a mobile video telephony terminal and a 10 mobile terminal Supporting only voice communication is BRIEF DESCRIPTION OF THE DRAWINGS referred-to as a mobile audio-dedicated terminal. FIG. 1 is a schematic diagram illustrating a call control The above features and advantages of the present invention system according to an exemplary embodiment of the present will be more apparent from the following detailed description invention. in conjunction with the accompanying drawings, in which: 15 Referring to FIG. 1, the call control system includes a FIG. 1 is a schematic diagram illustrating a call control mobile video telephony terminal 100, a mobile audio-dedi system according to an exemplary embodiment of the present cated terminal 300, and a mobile communication network invention; 200. In the call control system, the video telephony terminal FIG. 2 is a block diagram illustrating a configuration of the 100 transmits a video call request message (V call req) to mobile video telephony terminal of FIG. 1; the mobile communication network 200. In response to the FIG.3 is a block diagram illustrating a configuration of the V call req message, the mobile communication network 200 mobile audio-dedicated terminal of FIG. 1; transmits a video call setup message (V call set up) to the FIG. 4 is a diagram illustrating a message format of a video mobile audio-dedicated terminal 300. Upon receiving the call setup message according to an exemplary embodiment of V call set up message, the mobile audio-dedicated terminal the present invention; 25 300 sequentially transmits a disconnection message (Discon FIG. 5 is a flowchart illustrating a call control method for nect) and an audio call request message (A call req) to the mobile video telephony according to an exemplary embodi mobile communication network 200. When the Disconnect ment of the present invention; and A call req messages are received, the mobile communi FIG. 6 is a message flow diagram illustrating message cation network 200 transmits the Disconnectandan audio call flows in the call control system in association with the call 30 setup request message (A call set up) to the video tele control method of FIG. 5: phony terminal 100 such that an audio call link is established FIG. 7 is a schematic diagram illustrating a call control between the mobile video telephony terminal 100 and the system according to another exemplary embodiment of the mobile audio-dedicated terminal 300. present invention; FIG. 2 is a block diagram illustrating a configuration of the FIG. 8 is a flowchart illustrating a call control method for 35 mobile video telephony terminal 100 of FIG. 1. mobile video telephony according to another exemplary Referring to FIG. 2, the mobile video telephony terminal embodiment of the present invention; and 100 includes a first audio processing unit 120, a camera unit FIG. 9 is a message flow diagram illustrating message 140, a first keypad unit 110, a first display unit 150, a first flows in a call control system in association with the call memory unit 170, a first radio frequency (RF) unit 130, and a control method of FIG. 8. 40 first control unit 160. The first audio processing unit 120 is responsible for pro DETAILED DESCRIPTION OF THE INVENTION cessing an audio signal received through the first RF unit 130 to output the audio signal as an audible Sound wave through a Exemplary embodiments of the present invention are speaker (SPK), and for processing an audio signal input described with reference to the accompanying drawings in 45 through a microphone (MIC) to output as audio data to the detail. The same reference numbers are used throughout the first control unit 160. The audio data are synchronized with drawings to refer to the same or like parts. Detailed descrip Video data input through the camera unit 140 and then trans tions of well-known functions and structures incorporated mitted as a transmission signal when the mobile video tele herein may be omitted to avoid obscuring the Subject matter phony terminal 100 operates in an audiovisual communica of the present invention. 50 tion mode. Certain terminologies are used in the following description The camera unit 140 takes a picture and outputs the picture for convenience and reference only and are not to be consid as a video signal to the first control unit 160. The video signal ered limiting. In the following detailed description, only can be stored in the form of a file, temporarily or semi exemplary embodiments of the invention have been shown permanently, in the first memory unit 170. The camera unit and described, simply by way of illustration of the best mode 55 140 can take a still picture and a moving picture. In the contemplated by the inventors of carrying out the invention. audiovisual communication mode, the camera unit 140 can As will be realized, the invention is capable of modification in take a video stream such that the video stream is transmitted various obvious respects, all without departing from the through the first RF unit 130 in real time. At this time, the Scope and intent of the invention. Accordingly, the drawings transmission and reception video streams can be stored in the and description are to be regarded as illustrative in nature and 60 first memory unit 170 in the form of a motion picture file. The not restrictive. motion picture file can be temporarily stored and then In the following exemplary embodiments, at least two removed in consideration of the capacity of the first memory kinds of setup message are used for indicating a video call unit 170. setup and an audio call setup. The first keypad unit 110 is provided with a plurality of The mobile terminal can be any kind of terminal capable of 65 alphanumeric keys for furnishing user input data and various communication with a mobile communication system, Such function keys for executing specific operations. The function as a Personal Digital Assistant (PDA), laptop computer, keys may include navigation keys, Volume keys, and shortcut US 8,248,453 B2 5 6 keys. The first keypad unit 110 generates a key signal asso multiplexed signal to the first RF unit 130. The control signal ciated with a user configuration or a function control and includes a synchronization signal of the video and audio outputs the key signal to the first control unit 160. signals. The first display unit 150 presents various menu screens The first control unit 160 controls exchange of control associated with applications installed in the mobile video signals for establishing an audiovisual communication link telephony terminal 100 and information input by the user or and displaying information regarding the communication read from the first memory unit 170. Particularly, the first link setup status on the first display unit 150. The first control display unit 150 presents a motion picture taken by the cam unit 160 transmits V call req message to the mobile commu era unit 140 or received from another terminal, in an audio nication network 200 through the first RF unit 130 and visual communication session and communicates state infor 10 receives a Disconnect signal or Disconnect message from the mobile communication network 200 when it is not possible to mation. That is, the first display unit 150 displays information establish an audiovisual communication link with the called generated in response to user key input during an audiovisual party terminal. At this time, the first control unit 160 controls communication link establishment procedure and announce the first display unit 150 to display an announcement message ment message for notifying whether the audiovisual commu 15 of “audiovisual communication service is not available for nication link is successfully established or not. The example, in the form of a popup window. announcement message can be displayed in the form of a FIG. 3 is a block diagram illustrating a configuration of the popup window. The announcement message can be displayed mobile audio-dedicated terminal 300 of FIG. 1. with different content in accordance with a reason of the Referring to FIG. 3, the mobile audio-dedicated terminal audiovisual communication link establishment failure. For 300 includes an audio processing unit 320, a keypad unit 310, example, an announcement message “out of service area’ a display unit 350, a memory unit 370, an RF unit 330, and a may be displayed when the mobile video telephony terminal control unit 360. 100 is located in a blind area, or “audiovisual communication Detailed descriptions on the structures and functions iden service is not available' when a called party terminal is tical with those of the mobile video telephony terminal 100 of located in an area where the audiovisual communication ser 25 FIG. 2 are omitted hereinafter. Thus, the structures and func vice is not supported, or “non-video telephony terminal tions of the audio processing unit 320, memory unit 370, and when the called party terminal does not support an audiovi RF unit 330 are similar to those of the mobile video telephony sual communication. The first display unit 150 can be imple terminal 100 and need not be described in detail. mented with a liquid crystal display (LCD) operating with a The display unit 350 displays various menu screens of touchscreen. In this case, the first display unit 150 can be an 30 Voice-communication applications and information input by input device. the user or read from the memory unit 370. Particularly, the The first memory unit 170 stores applications associated display unit 350 is controlled to display an announcement with the video telephony and video data generated while notifying the reception of a video call request message executing the video telephony applications. The first memory (V call req) and the unavailability of the audiovisual com unit 170 is also responsible for buffering the audio and video 35 munication (for example, “missed call’). After the video call stream to and from the called party terminal. The memory unit request is rejected, the mobile audio-dedicated terminal 300 may include a program region and a data region. attempts to establish a voice communication link. In this case, The program region stores an operating system (OS) for the display unit 370 is controlled to display information controlling general operation of the mobile video telephony thereto on the mobile video telephony terminal 100, e.g. a terminal 100 and applications associated with various Supple 40 phone number of the mobile video telephony terminal 100, or mental functions such as camera, audio and video file play a preset outgoing call image. After the Voice communication back and audiovisual communication functions. The applica link is established, the display unit 370 is controlled to display tions are executed by a user command under the control of the a preset on-line image. The display unit 370 can be imple first control unit 160. mented with an LCD with a touchscreen. In this case, the The data region stores application data generated by the 45 display unit 370 can also be an input device. applications, such as still and motion pictures, phone book The control unit 360 controls generation operations of the data, audio files, and user information. The data region also mobile audio-dedicated terminal 300 and cooperative signal can store the video stream transmitted to or received from the ing operations among the internal units. The control unit 360 counterparty terminal temporarily or semi-permanently can be implemented with a modem and a codec for Voice according to a user's selection. 50 signals. The first RF unit 130 is responsible for processing control The control unit 360 generates and transmits a disconnec signals associated with an audiovisual communication link tion message (Disconnect) in response to the V call set up establishment and video and audio signals during an audio message transmitted by the mobile communication network visual communication session, to be transmitted to or 200. The control unit 360 extracts a phone number of the received from a counterparty terminal. The first RF unit 130 55 calling party terminal, i.e. the mobile video telephony termi includes an RF transmitter for up-converting and amplifying nal 100, from V call set up message, and attempts to estab a baseband signal to be transmitted and an RF receiver lish a voice communication link to the phone number. FIG. 4 capable of low noise amplifying and down-converting a is a diagram illustrating an exemplary message format of a received radio frequency signal. V call set up message according to another exemplary The first control unit 160 controls generation operations of 60 embodiment of the present invention. As shown in FIG. 4. the mobile video telephony terminal 100 and cooperative V call set up message includes a calling party binary coded signaling operations among the internal units. The first con decimal (BCD) number representing a phone number. In trol unit 160 can be implemented with a modem and a codec more detail, if V call set up message for an audiovisual for compressing/decompressing the audio and video data. communication is received, the mobile audio-dedicated ter The first control unit 160 controls the video telephony 65 minal 300 transmits a Disconnect signal to the mobile video function and includes a multiplexer/demultiplexer for multi telephony terminal 100 through the mobile communication plexing video, audio, and control signals, and outputting a network 200 so as to terminate the audiovisual communica US 8,248,453 B2 7 8 tion establishment procedure. Next, the mobile audio-dedi At step S105, the mobile audio-dedicated terminal 300 can cated terminal 300 transmits A call req to the mobile com also be configured to record the missed call in a log file munication network 200 and thus the mobile communication without displaying a missed call announcement message. network 200 transmits. A call set up message to the calling Next, the mobile audio-dedicated terminal 300 transmits party terminal, i.e. the mobile video telephony terminal 100, an audio call request message (A call req) to the mobile with reference to the phone number contained in communication network 200 (S106). The A call req mes V call set up message. sage is transmitted together with the phone number of the A call type can be recognized by referring to an Informa mobile video telephony terminal 100 obtained from the tion Transfer Capability field of V call set up message. The V call set up message. 10 Upon receiving the A call req message, the mobile com Information Transfer Capability field of the V call set up munication network 200 generates and transmits an audio call message contains a value indicating the call type, i.e. an audio setup message (A call set up) to the mobile video telephony call, a data call, or a video call. terminal 100 (S107). With the acceptance of audio commu The control unit 360 obtains the phone number of the nication by the mobile video telephony terminal 100, a voice calling party terminal, i.e. the mobile video telephony termi 15 communication link is established between the mobile video nal 100, from the V call set up message. The phone number telephony terminal 100 and the mobile audio-dedicated ter of the mobile video telephony terminal 100 is contained in the minal (109). Calling Party BCD Number field of V call set up message. The phone number of the mobile video telephony terminal The control unit 360 controls the display unit 350 to display 100 is obtained from the Calling Party BCD Number field of a missing call announcement when V call set up message the V call set up message. from the mobile communication network 200 is received. At step S103, if the call setup request is not for an audio Although the mobile video telephony terminal and the visual communication, i.e. the Information Transfer Capabil mobile audio-dedicated terminal are depicted as shown in ity field of the V call set up message indicates an audio call FIGS. 2 and 3, respectively, their configurations can be modi or a data call, the mobile audio-dedicated terminal 300 per fied by adding other functional modules such as a digital 25 forms a corresponding call setup process (S108). broadcast receiver. In this manner, the mobile audio-dedicated terminal 300 A call control operation of the above-structured call control performs an audio call setup process in response to a video system is described hereinafter with reference to the accom call setup message, and it is possible for the mobile video panying drawings. telephony terminal 100 to avoid unnecessarily retrying the FIG. 5 is a flowchart illustrating a call control method for a 30 video call. mobile video telephony according to another exemplary FIG. 7 is a schematic diagram illustrating a call control embodiment of the present invention, and FIG. 6 is a message system according to another exemplary embodiment of the flow diagram illustrating message flows in a call control sys present invention. tem in association with the call control method of FIG. 5. Referring to FIG. 7, the call control system includes the 35 mobile video telephony terminal 100 supporting audiovisual Referring to FIGS. 5 and 6, the mobile video telephony communication and a voice communication, the mobile terminal 100 transmits a video call request message (V call audio-dedicated terminal 300, and the mobile communica req) to the mobile communication network 200 (S101). Upon tion network 200 for providing the mobile audiovisual and receiving the V call req message, the mobile communica Voice telephony services. tion network 200 transmits a video call setup message 40 The mobile video telephony terminal 100 transmits a video (V call set up) corresponding to the V call req message to call request message (V call req) to the mobile communica the mobile audio-dedicated terminal 300 (S102). tion network 200 together with a phone number of the mobile The V call set up message includes an Information audio-dedicated terminal 300. In response to the V call req Transfer Capability field set to “video call’, a calling party message, the mobile communication network 200 transmits a phone number for the mobile video telephony terminal 100, 45 Video call setup message (V call set up) to the mobile and a called party phone number for the mobile audio-dedi audio-dedicated terminal 300. Upon receiving the cated terminal 300. V call set up message, the mobile audio-dedicated terminal When the V call set up message is received, the mobile 300 transmits an audiovisual communication incapability audio-dedicated terminal 300 checks the V call set up mes message (Do not set up) to the mobile video telephony ter sage to determine whether the call setup request is for an 50 minal 100 through the mobile communication network 200 in audiovisual communication (S103). response to the V call set up message. Upon receiving the The mobile audio-dedicated terminal 300 can recognize a Do not set up, the mobile video telephony terminal 100 requested call type with a value of the Information Transfer transmits an audio call request message (A call req) to the Capability field of the V call set up message. The call type mobile communication network 200, and the mobile commu can be one of an audio call, a data call, and a video call. 55 nication network 200 generates and transmits an audio call If the V call set up message includes video call identifier, setup message (A call set up) to the mobile audio-dedicated the mobile audio-dedicated terminal 300 rejects the terminal 300 in response to the A call req message. Accord V call set up message and transmits a disconnection mes ingly, a Voice communication link is established between the sage (Disconnect) to the mobile video telephony terminal 100 mobile video telephony terminal 100 and the mobile audio through the mobile communication network 200 (S104). The 60 dedicated terminal 300. mobile audio-dedicated terminal 300 may then display an The mobile video telephony terminal 100 can be config announcement message, e.g. “Missed Call”, on a display ured to automatically transmit the A call req message when screen (S105). the Do not set up message is received from the mobile The mobile video telephony terminal 100 can be config audio-dedicated terminal 300. The mobile video telephony ured to display an announcement message, e.g. "audiovisual 65 terminal 100 can be configured to transmit the A call req communication disabled', on its display screen when the message when a voice communication transit request mes Disconnect message or signal is received. sage (A call Transit 2) is received from the mobile commu US 8,248,453 B2 10 nication network 200. In this case, the mobile communication display Screen in the form of a popup window to enable a user network 200 checks a type of the mobile audio-dedicated to decide whether to change the call type. terminal 300 from information stored in a Home Location In accordance with a command for changing the call type in Register on the mobile audio-dedicated terminal 300, and put by the user, the mobile video telephony terminal 100 transmits the A call Transit 2 message when it is deter 5 generates an audio call request message (A call req) (S206) mined that the mobile audio-dedicated terminal 300 has no and transmits the A call req message to the mobile commu audiovisual communication capacity on the basis of the type nication network 200 (S207). In response to the A call req information. message, the mobile communication network 200 generates FIG. 8 is a flowchart illustrating a call control method for and transmits an audio call setup message (A call set up) to mobile video telephony according to another exemplary 10 embodiment of the present invention, and FIG.9 is a message the mobile audio-dedicated terminal 300 (S208). With the flow diagram illustrating message flows in a call control sys acceptance of Voice communication by the mobile audio tem in association with the call control method of FIG. 8. dedicated terminal 300, a voice communication link is estab Since the mobile video telephony terminal 100 and the lished between the mobile video telephony terminal 100 and mobile audio-dedicated terminal 300 have identical struc 15 the mobile audio-dedicated terminal 300 (S209). tures and functions to those in FIGS. 2 and 3, the call control At step S205, if the A call Transit 2 message is not method is described with the references used in FIGS. 5 and received within a predetermined time duration, the mobile 6. video telephony terminal 100 automatically generates the Referring to FIGS. 8 and 9, in the call control method A call req (S210) and then transmits the A call req to the according to this exemplary embodiment of the present inven mobile communication network (S207). tion, the mobile video telephony terminal 100 transmits video At step S203, if the call setup request is not for an audio call request message (V call req) to the mobile communica visual communication, the mobile-voice dedicated terminal tion network 200 (S201). Upon receiving the V call reqmes 300 performs a process for establishing a voice or data com sage, the mobile communication network 200 generates and munication link (S211). transmits a video call setup message (V call set up) to the 25 The above-described methods according to the present mobile audio-dedicated terminal 300 (S202). invention can be realized in hardware or as Software or com The V call set up message includes information on a call puter code that can be stored in a recording medium such as a type, a calling party phone number for the mobile video CD ROM, an RAM, a floppy disk, a hard disk, or a magneto telephony terminal 100 and a called party phone number for optical disk or downloaded over a network, so that the meth the mobile audio-dedicated terminal 300. 30 ods described herein can be rendered in Such software using When the V call set up message is received, the mobile a general purpose computer, or a special processor or in audio-dedicated terminal 300 checks the V call set up mes sage to determine whether the call setup request for an audio programmable or dedicated hardware, Such as an ASIC or visual communication. FPGA. As would be understood in the art, the computer, the The V call set up message includes a Calling Party BCD 35 processor or the programmable hardware include memory Number field indicating a calling party phone number and an components, e.g., RAM, ROM, Flash, etc. that may store or information Transfer Capability filed indicating a call type receive Software or computer code that when accessed and such the mobile audio-dedicated terminal 300 can recognize executed by the computer, processor or hardware implement the requested call type and the calling party number of the the processing methods described herein. mobile video telephony terminal 100. The call type can be one 40 Although exemplary embodiments of the present invention of an audio call, a data call, and a video call. are described in detail hereinabove, it should be clearly under If the V call set up message includes a video call identi stood that many variations and/or modifications of the basic fier, the mobile audio-dedicated terminal 300 generates and inventive concepts herein taught which may appear to those transmits an audiovisual communication incapacity message skilled in the present art will still fall within the spirit and (Do not set up) to the mobile video telephony terminal 100 45 Scope of the present invention, as defined in the appended through the mobile communication network 200 in response claims. to the V call set up message (S204). As described above, the call control system and method for After receiving the Do not set up message, the mobile a mobile communication according to the present invention video telephony terminal 100 determines whether an audio enable a calling party video telephony terminal to recognize a call transit request message (A call Transit 2) is received 50 capacity of a called party terminal, thereby avoiding unnec from the mobile communication network (205). essary video call setup attempts. The A call Transit 2 is transmitted when the mobile Also, the call control system and method of the present video telephony terminal 100 registers an option for notifying invention establish a communication link between two termi a counterparty capacity to the mobile communication net nals in consideration of capabilities of the two terminals such work 200 as a supplementary function. In the case that the 55 that the terminals having different capabilities can communi counterparty capacity notification option is registered, the cate with each other, resulting in improvement of call setup mobile communication network 200 obtains information on reliability. the capability of the called party terminal (in this embodi ment, the mobile audio-dedicated terminal 300) from a Home What is claimed is: Location Register (HLR) and transmits the A call Transit 2 60 1. A call control method for establishing communication message to calling party terminal (in this embodiment, the between mobile terminals having different capabilities, com mobile video telephony terminal 100) if the called party ter prising the steps of: minal does not support the audiovisual communication. The receiving, at a called party terminal, a call setup message; counterparty capability notification option can be disabled. transmitting a disconnection message to a calling party If the A call Transmit 2 message is received from the 65 terminal in response to the call setup message; and mobile communication network 200, the mobile video tele performing a call setup procedure triggered by the called phony terminal 100 displays an announcement message on a party terminal. US 8,248,453 B2 11 12 2. The call control method of claim 1, wherein the step of response to the video call setup message, and transmit transmitting a disconnection message comprises the step of ting an audio call request message to a calling party generating the disconnection message if the call setup mes terminal; Sage includes a video call identifier. an audio processing unit for processing an audio signal 3. The call control method of claim 1, wherein performing generated during a communication session; and a call setup procedure comprises the steps of: a control unit for controlling automatic transmission of the extracting a phone number of the calling party terminal disconnection message and the audio call request mes from the call setup message; Sage. generating an audio call request message with the phone 14. The terminal of claim 13, further comprising a display number of the calling party terminal; and 10 unit for displaying a missed call alert message in response to transmitting the audio call request message to the calling the transmission of the disconnection message. party terminal. 15. A call control system, comprising: 4. The call control method of claim 1, further comprising a video telephony terminal which transmits a video call the step of: 15 request message; displaying an announcement message indicating that an an audio-dedicated terminal which transmits a disconnec unavailable call is received. tion message to the video telephony terminal in response 5. The call control method of claim 4, wherein the to the video call request message; and announcement message is a missed call alert message. a mobile communication network for Supporting commu 6. The call control method of claim 1, wherein the call nication between the video telephony terminal and the setup message includes a call type identifier for indicating audio-dedicated terminal. one of an audio call, a data call, and a video call. 16. The call control system of claim 15, wherein the video 7. A call control method for a mobile communication sys telephony terminal comprises: tem including a video telephony terminal, an audio-dedicated a camera for generating a video stream for an audiovisual terminal, and a mobile communication network Supporting 25 communication; communication between the terminals, comprising: an audio processing unit for processing an audio signal transmitting, at the video telephony terminal, a video call associated with the audiovisual communication; request message to the mobile communication network; a radio frequency unit for transmitting an audio call setup transmitting, at the mobile communication network, a message to the audio-dedicated terminal, and establish Video call setup message to the audio-dedicated terminal 30 ing a communication channel with the audio-dedicated terminal; in response to the video call request message; a keypad unit for generating key input signals for executing transmitting, at the audio-dedicated terminal, a disconnec an operation of the camera and audiovisual communi tion message to the video telephony terminal through the cation; and mobile communication network in response to the video 35 a control unit for controlling cooperative signaling among call setup message; and the camera, audio processing unit, RF unit, and keypad transmitting, at the audio-dedicated terminal, an audio call unit, and controlling establishment of audiovisual com request message to the mobile communication network. munication and Voice communication links. 8. The call control method of claim 7, whereintransmitting 17. The call control system of claim 16, wherein the video a disconnection message comprises the steps of 40 telephony terminal further comprises: generating the disconnection message if the video call a display unit. setup message includes a video call identifier. 18. The call control system of claim 15, wherein the audio 9. The call control method of claim 7, whereintransmitting dedicated terminal comprises: an audio call request message comprises the steps of: a radio frequency unit for receiving a video call setup extracting a phone number of the video telephony terminal 45 message from the video telephony terminal, transmit from the video call setup message; ting a disconnection message in response to the video generating the audio call request message with the call setup message, and transmitting an audio call extracted phone number, and request message to the video telephony terminal; transmitting, at the mobile communication network, an an audio processing unit for processing an audio signal in audio call setup message to the video telephony terminal 50 association with a voice communication; and in response to the audio call request message received a control unit for controlling transmission of the discon from the audio-dedicated terminal. nection message and the audio call request message. 10. The call control method of claim 7, further comprising 19. The call control system of claim 18, wherein the audio the step of: dedicated terminal further comprises: displaying an announcement message indicating that an 55 a display unit. unavailable call is received on a display screen when the 20. The call control system of claim 18, wherein the control disconnection message is transmitted. unit controls extraction of a phone number of the video tele 11. The call control method of claim 7, further comprising phony terminal from the video call setup message and trans the step of: mitting the audio call request with the extracted phone num displaying a missed call alert message on a display Screen 60 ber. when the disconnection message is transmitted. 21. A call control method for a mobile terminal, compris 12. The call control method of claim 7, wherein the video ing the steps of call setup message includes a call type identifier for indicat transmitting a video call request message; ing one of an audio call, a data call, and a video call. receiving an audiovisual communication unavailable mes 13. A mobile terminal, comprising: 65 Sage in response to the video call request message; and a radio frequency unit for receiving a video call setup transmitting an audio call request message in response to message, transmitting a disconnection message in the audiovisual communication unavailable message. US 8,248,453 B2 13 14 22. The call control method of claim 21, further comprising transmitting, at the video telephony terminal, an audio call the step of: request message to the mobile communication network; receiving an audio call transmit message after receiving the and transmitting, at the mobile communication network, an audiovisual communication unavailable message. audio call setup message to the audio-dedicated terminal 23. The call control method of claim 21, further comprising in response to the audio call request message. the step of: 24. The call control method of claim 23, further comprising providing a plurality of mobile terminals, including a video the step of: telephone terminal and an audio-dedicated terminal; transmitting, at the mobile communication network, an transmitting, at the video telephony terminal, the video call audio call transit message to the video telephony termi request message to a mobile communication network; nal in response to receiving the disconnection message transmitting, at the mobile communication network, a from the audio-dedicated terminal. Video call setup message to the audio-dedicated terminal 25. The call control method of claim 24, whereintransmit in response to the video call request message; ting an audio call transit message comprises the step of: transmitting, at the audio-dedicated terminal, a disconnec checking a type of the audio-dedicated terminal; and tion message to the video telephony terminal through the generating the audio call transit message if the type of the mobile communication network in response to the video audio-dedicated terminal is an audio-dedicated type. call setup message; k k k k k