Method for expanding concurrent incoming call volume of VoIP equipment based on SIP message

Abstract

The invention discloses a method for expanding the concurrent incoming call amount of VoIP (Voice over Internet Protocol) equipment based on an SIP (Session Initiation Protocol) message, and belongs to the related field of VoIP. Specifically, aiming at VoIP equipment A to initiate a call, a user sets a number and a call type of opposite-end equipment B; whether a standard SIP calling process is used or not is judged, and if yes, normal calling is carried out; otherwise, the device A sends a pre-call initiating short message to the device B, and at the moment, the device B allows the multiple devices to call concurrently; then, an event processing module of the equipment B calls a short message to send a response pre-call message to the equipment A, stores a corresponding call event in a call list, and transmits the call event to a user interface module of the equipment B to display an incoming call reminder with the same style as the standard SIP call; the user B0 presses the entity or virtual key to select to accept the pre-call, reject the pre-call or transfer the pre-call; the event processing module of the device B carries out key event processing; according to the invention, the concurrent incoming call amount of the VoIP equipment is improved; the conversion from the SIP message to the call control logic is realized.

Description

Technical Field

[0001] The invention belongs to the field related to VoIP (Voice over Internet Protocol, voice transmission based on IP), and specifically is a method for expanding the concurrent incoming call volume of VoIP equipment based on SIP (Session Initialization Protocol, Session Initialization Protocol) messages. Background Art

[0002] With the continuous advancement of audio and video communication technology, its user scale is also expanding rapidly, and the demand for calls based on this communication technology is also increasing.

[0003] VoIP devices have the advantages of privacy protection, rich functions and low call costs, and are widely used in various high-frequency and high-load communication scenarios such as factories, computer rooms, medical treatment, transportation, and commerce. However, a VoIP device terminal has limited computing power, and calls that exceed the device's processing capacity will be directly discarded. If the customer group happens to be sensitive to message discarding and cannot tolerate call loss, the discarding behavior of the VoIP device will reduce the experience satisfaction of the above customer group.

[0004] SIP message refers to a short message service based on SIP, which provides a point-to-point text transmission capability between VoIP devices. Compared with standard SIP calls, the reception and transmission of SIP messages have lower performance requirements for devices due to the simplicity of implementation and the small amount of data transmitted. Therefore, if after the caller initiates the call but before it is connected, a standard SIP call is not initiated, but SIP messages are used to pre-negotiate call-related information, and the timing of creating a standard SIP call is postponed until the called party picks up the call, the consumption of limited resources of the VoIP device in processing standard SIP calls can be reduced, and the number of incoming calls that are not connected by the VoIP device can be effectively increased.

[0005] VoIP products are based on SIP and have the hardware and software foundation for sending and receiving SIP messages. Therefore, there is no need to modify the existing hardware, and the software can support SIP message pre-negotiation calls, which can not only meet the needs of some specific application scenarios, save some expenses, but also facilitate the promotion of VoIP equipment. Summary of the invention

[0006] In view of the above problems existing in the prior art, the present invention provides a method for expanding the concurrent incoming call volume of VoIP devices based on SIP messages. By converting SIP messages into call control logic, pre-call initiation, pre-call hang-up and pre-call transfer functions are realized, and a user interface consistent with standard SIP calls is provided. Users can easily get started and can use it without additional operational knowledge reserves.

[0007] The method for converting the SIP message into call control logic comprises the following specific steps:

[0008] Step 1: For the VoIP device A that is to initiate a call, user A0 sets the number and call method type of the other party's VoIP device B to the function button DSS Key of device A;

[0009] Each VoIP device includes a user input module, a text message control module, a call control module, an event processing module and a user interface module.

[0010] The user input module is responsible for receiving key events of physical keys and virtual keys on the touch screen, and distributing them to the event processing module;

[0011] The SMS control module is responsible for sending and receiving SMS messages and distributing SMS events to the event processing module;

[0012] The call control module is responsible for call operations such as initiating, hanging up, and transferring, and distributes call events to the event processing module;

[0013] The event processing module first receives the SMS message sent by the other party, responds to the other party to indicate that the call has been received and stored locally, then the local call list changes, thereby triggering a change in the user interface, and finally, when the user presses a button, the user interface module calls the event processing module to continue processing according to the user's selection;

[0014] The user interface module is responsible for presenting events to the user in the form of screen images and speaker sounds.

[0015] The call method types include: standard SIP call type, or call type based on SIP message expansion of the concurrent incoming call volume of the VoIP device.

[0016] Step 2: When user A0 presses the function key DSS Key, device A determines whether to use the standard SIP call process according to the configured call method type. If yes, the call control module of device A is called to call the number of device B; otherwise, it goes to step 3;

[0017] Step 3: Device A selects the call type based on SIP message expansion of concurrent incoming calls of VoIP devices, that is, calls the sending interface of the SMS control module to send a pre-call SMS to the number of device B. At this time, device B allows multiple devices to make concurrent incoming calls;

[0018] The pre-call SMS includes a protocol header and a protocol body;

[0019] The From field in the protocol header contains the number of device A; the To field contains the number of device B.

[0020] The protocol body contains:

[0021] The cid field indicates the pre-call ID, which identifies different pre-calls of the VoIP device;

[0022] The event field indicates the call event operation to be performed on the call, including initiating pre-call invite, responding to pre-call invite back, calling party hanging up pre-call end, called party hanging up pre-call know, and transferring pre-call unattended;

[0023] Other business information: other information required by the actual business, including protocol version number version, message priority callType, device name callUser, device ID, device IP address, device MAC address and device location information, etc.

[0024] Step 4: The SMS control module of device B receives the pre-call SMS and transmits it to its own event processing module; the event processing module calls the SMS control module to send a response pre-call message to device A, indicating that the call is received;

[0025] Step 5: The event processing module of device B stores the call event corresponding to the pre-call SMS in the call list, and transmits it to the user interface module to update the call status, that is, display an incoming call reminder in the same style as a standard SIP call;

[0026] Step 6: User B0 presses the physical button of device B or the virtual button on the screen to select accept, reject or transfer the pre-call;

[0027] Step 7: The user input module of device B receives the key event and transmits it to the event processing module for key event processing:

[0028] If user B0 chooses to accept the pre-call, device B calls the call control module to actively initiate a standard SIP call to device A, that is, the standard SIP call that should have been initiated by device A to device B is postponed, and device B becomes the call initiator. At the same time, device A will automatically answer the call to user A0, causing the caller to be connected;

[0029] If user B0 chooses to reject the pre-call, device B sends a hang-up pre-call message to the peer device A indicating that the call is actively rejected;

[0030] The hang-up pre-call message body includes the following fields:

[0031] endUser field: the number of device B;

[0032] endType field: reason for hang-up; 0 means device A received the hang-up from device B, 1 means the hang-up was caused by device B not answering the call due to timeout, 2 means device A actively hung up, and 3 means the hang-up was caused by call priority adjustment.

[0033] If user B0 selects transfer pre-call, user B0 should enter the number of device C for transfer pre-call and select the call type. Device B sends a transfer pre-call message to the other device A, indicating that a call is initiated again to device C according to the selected call type.

[0034] The transfer pre-call message body includes the following fields:

[0035] tranferTargetUser field: the number of device C;

[0036] tranferTargetDevice field: call type;

[0037] tranferTargetIp field: IP address of device C.

[0038] The advantages of the present invention are:

[0039] A method for expanding the concurrent incoming call volume of VoIP equipment based on SIP messages, based on VoIP products that support SIP messages, to increase the concurrent incoming call volume of VoIP equipment; to achieve the conversion of SIP messages to call control logic; to achieve a user operation interface consistent with standard SIP calls, thereby reducing the skill requirements of VoIP equipment users and facilitating user use. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A flow chart of a method for expanding the concurrent incoming call volume of a VoIP device based on SIP messages according to the present invention;

[0041] Figure 2 A schematic diagram of the communication between VoIP devices performing a pre-call process according to an embodiment of the present invention. DETAILED DESCRIPTION

[0042] In order to facilitate those skilled in the art to understand and implement the present invention, the present invention is described in further detail and in depth with reference to the accompanying drawings.

[0043] The present invention discloses a method for expanding the concurrent incoming call volume of VoIP devices based on SIP messages, which is as follows: the user uses a VoIP device that supports this method to configure the device number and call method to be called on the function button DSS Key. After the user presses the DSS Key, the device will pre-negotiate with the remote VoIP device through SIP information, and the called device will display an incoming call message in the same style as a standard SIP call. After the pre-call is initiated, it supports the call initiator to hang up, the call recipient to hang up, and the call recipient to pre-call transfer. Figure 1 As shown, the specific steps are as follows:

[0044] Step 1: For the VoIP device A that is to initiate a call, user A0 sets the number and call method type of the other party's VoIP device B to the function button DSS Key of device A;

[0045] Each VoIP device includes a user input module, a text message control module, a call control module, an event processing module and a user interface module.

[0046] The user input module is responsible for receiving key events of physical keys and virtual keys on the touch screen, and distributing them to the event processing module;

[0047] The SMS control module is responsible for sending and receiving SMS messages and distributing SMS events to the event processing module;

[0048] The call control module is responsible for call operations such as initiating, hanging up, and transferring, and distributes call events to the event processing module;

[0049] The event processing module first receives the SMS message sent by the other party, responds to the other party to indicate that the call has been received and stores it locally, then the call list corresponding to the local call event changes, thereby triggering a change in the user interface, and finally, when the user presses a button, the user interface module calls the event processing module to continue processing according to the user's selection;

[0050] The user interface module is responsible for presenting events to the user in the form of screen images and speaker sounds.

[0051] The call method types include: standard SIP call type, or call type based on SIP message expansion of the concurrent incoming call volume of the VoIP device.

[0052] Step 2: When user A0 presses the function key DSS Key, device A determines whether to use the standard SIP call process according to the configured call method type. If yes, the call control module of device A is called to call the number of device B; otherwise, it goes to step 3;

[0053] Step 3: Device A selects the call type based on SIP message expansion of concurrent incoming calls of VoIP devices, that is, calls the sending interface of the SMS control module to send a pre-call SMS to the number of device B. At this time, device B allows multiple devices to make concurrent incoming calls;

[0054] Device A does not initiate a SIP call but sends a pre-call SMS to deliver the incoming call information. Since the resource consumption of SIP SMS is lower than that of SIP call, more devices are allowed to call device B at the same time, which increases the concurrent incoming call volume of device B.

[0055] The pre-call SMS includes a protocol header and a protocol body;

[0056] The From field in the protocol header is like "6"<sip:6@1.hotspot> ; tag = 596308316, contains the number of device A; the To field is like "0"<sip:0@1.hotspot> , containing the number of device B.

[0057] The protocol body looks like this:

[0058] {"version":"0.1","cid":53,"event":"invite","event.params":{"deviceType":"Y501W-Y","callType":0,"port":0,"areaSn":1,"r oomName":3,"bedName":0,"bedCode":1,"url":"","bindingCode":"","callIp":"172.16.66.208","callUser":"802617"},"type":"0"}

[0059] CID field: pre-call ID, identifying different pre-calls of VoIP devices;

[0060] Event field: the call event operation to be performed by the call, including initiating pre-call invite, responding to pre-call invite back, calling party hanging up pre-call end, called party hanging up pre-call know, and transferring pre-call unattended;

[0061] Other business information: other information required by the actual business, such as protocol version number version, message priority callType, device name callUser, device ID, device IP address, device MAC address, device location information, etc.

[0062] Step 4: The SMS control module of device B receives the pre-call SMS and transmits it to its own event processing module; the event processing module calls the SMS control module to send a response pre-call message to device A, indicating that the call is received;

[0063] The response pre-call message body is as follows:

[0064] {"version":"0.1","cid":55,"event":"invite back","event.params":{"calledUser":"802617","calledIp":"172.16.66.6"},"type":"0"}

[0065] Step 5: The event processing module of device B stores the call event corresponding to the pre-call SMS in the call list, and transmits it to the user interface module to update the call status, that is, display an incoming call reminder in the same style as a standard SIP call;

[0066] Step 6: User B0 presses the physical button of device B or the virtual button on the screen to select accept, reject or transfer the pre-call;

[0067] Step 7: The user input module of device B receives the key event, and the event processing module processes the key event:

[0068] If user B0 chooses to accept the pre-call, device B calls the call control module to actively initiate a standard SIP call to device A, that is, the standard SIP call that should have been initiated by device A to device B in step 2 is postponed to this step and device B becomes the call initiator. At the same time, device A will automatically answer the call to user A0, causing the caller to be connected;

[0069] If user B0 chooses to reject the pre-call, device B sends a hang-up pre-call message to the peer device A indicating that the call is actively rejected;

[0070] The hang-up pre-call message body is as follows:

[0071] {"version":"0.1","cid":53,"event":"end","event.params":{"endUser":"802617","endType":2,"areaSn":1},"type":"0"}

[0072] endUser field: the number of device B;

[0073] endType field: reason for hangup. 0 means device A received the hangup from device B, 1 means the hangup was caused by device B not answering the call due to timeout, 2 means device A actively hung up, and 3 means the hangup was caused by call priority adjustment.

[0074] If user B0 selects transfer pre-call, user B0 should enter the number of the transfer device C and select the call type, and device B sends a transfer pre-call message to the other device A indicating that the above type should be used to initiate a call to device C again.

[0075] The transfer pre-call message body is as follows:

[0076] {"version":"0.1","cid":"55","event":"unattended","event.params":{"tranferTargetUser:"002","tranferTargetDevice":"NurseStationDevice","tranferTargetIp":"172.16.20.20"},"type":"0"}

[0077] tranferTargetUser field: the number of device C;

[0078] tranferTargetDevice field: call type;

[0079] tranferTargetIp field: IP address of device C.

[0080] Example:

[0081] like Figure 2 Shown, including Figure 2 aThe called party hangs up the pre-call principle, Figure 2 b. Principle of pre-call after the calling party hangs up. Figure 2 c The called party answers the pre-call principle. Figure 2 d. Principle of initiating a standard SIP call after transferring the pre-call; Figure 2 e-transfer pre-call and initiate pre-call principle; the specific steps are as follows:

[0082] Step 1: For the VoIP device A that wants to initiate a call, user A0 sets the number and call method type of the other device B to the function button DSS Key of device A;

[0083] The specific configuration process is: through the friendly interface of VoIP device A, user A0 enters necessary parameters for the function keys according to the instruction manual; or accesses the background management system provided by VoIP device A through a browser, and the user enters relevant call parameters in the function key setting interface in the configuration page.

[0084] Parameters include: device number and calling method type;

[0085] Step 2: When user A0 presses the DSS Key function button, device A determines whether to use the standard SIP call process or the pre-call process according to the configured call method type;

[0086] When user A0 presses the DSS Key function key configured on VoIP device A, the user input module receives the key press and release events, and notifies the event processing module to read the key parameter configuration information of the DSS Key and write it into the key event, which is then transmitted to the event processing module for judgment.

[0087] Key events refer to the state and duration of the hardware physical keys set by VoIP device A or the virtual keys on the touch screen, and the data information transmitted to other modules by the user input module;

[0088] Step 3: According to the user's selection, if the standard SIP call process is used, the call control module is called to call the configured peer VoIP device B number; if the pre-call process is used, the sending interface of the SMS control module is called to send a pre-call SIP SMS to the peer device B number;

[0089] The event processing module builds a standard VoIP call request or a pre-call request based on the call line that has been successfully registered in advance or other call lines specified by the user and the set call type. If the call type of the DSS Key is set to the pre-call type, a pre-call request is built, that is, the sending interface of the SMS control module is called to create a SMS containing pre-call information, create a UDP or TCP socket, and send the pre-call information from the socket to the SIP server or the peer VoIP device B via Ethernet.

[0090] A call line is a SIP line, which is a telephone line that uses the SIP protocol for communication. A call line should support:

[0091] 1) Registration: Before initiating a call or other data communication, the VoIP device needs to provide its own IP address and the network protocol and network port used for VoIP communication to the SIP server.

[0092] 2) Signaling forwarding: After the aforementioned registration process, the SIP server should be able to forward request messages and response messages such as call initiation, call termination, call transfer, call renegotiation, and information sending to both parties based on the device number.

[0093] Pre-call SIP SMS is based on the SIP SMS function (a method for SIP protocol to exchange text in a communication system) and is a method for implementing pre-call negotiation.

[0094] The SIP message header stores the peer device number. The message body of the SIP message contains the necessary parameters for pre-negotiated calls. The message body should include:

[0095] 1) Device protocol version number: refers to the protocol stack version number that processes the pre-call negotiation information. The communicating parties can provide different communication service capabilities or different business processing logic according to different version numbers;

[0096] 2) Device IP address: refers to the IP address of the device that sends the pre-call negotiation information. In order to meet the availability of device communication and effectively improve the disaster recovery capability of VoIP communication, when the device number used by the VoIP device is abnormal and cannot be called normally, it will try to bypass the VoIP communication intermediate device SIP server and directly continue negotiation or pre-negotiation with the IP address of the other end VoIP device;

[0097] 3) Pre-call ID: refers to the identifier of a call between a pair of VoIP devices. When a pair of VoIP devices are processing the same pre-call, they should use the same pre-call ID in their signaling. The significance of the pre-call ID is to distinguish different calls between a pair of VoIP devices, and to prevent the call logic processing errors caused by the cross-signaling and mutual interference of different calls caused by device freezes, network delays, etc. when both VoIP devices are processing multiple calls;

[0098] 4) Pre-call event type: including five signaling types, namely, initiate pre-call, respond to pre-call, caller hang-up pre-call, called party hang-up pre-call and transfer pre-call;

[0099] 5) Other business information: Other business information fields allow VoIP developers to expand other business information required during the pre-call process, such as message priority, device name, device ID, device MAC address, and device location information. Its functions include: adding, deleting, and modifying text information, picture information, voice information, animation information, ringtones, reminder sounds, and alarm sounds displayed to users in the user interface module; setting the duration and number of times the user interface module displays information; dynamically modifying the business logic of the event processing module, such as whether to write call records, set the ringtone volume of the called device, whether to push relevant business information to other external devices physically connected to this VoIP device, whether to write relevant business information to the built-in storage of this VoIP device, and whether to upload relevant business information to other terminals or servers that have established network communications with the VoIP device in various forms such as XML, CSV, and JSON; and so on.

[0100] Step 4: The SMS control module of the called device B receives the pre-call SMS and transmits it to the event processing module; the event processing module calls the SMS control module to send a response pre-call message indicating that the call has been received to the device A that initiated the pre-call;

[0101] If the initiating VoIP device A does not receive the confirmation message specified by the SIP protocol for the pre-call information of the peer B, that is, the SIP protocol stack of the peer has timed out processing the SIP message, the initiating end A will try to retransmit according to the interval specified by the SIP protocol standard; if the initiating VoIP device A does not receive the response pre-call information of the peer using the same pre-call ID, that is, the pre-call protocol stack of the peer has timed out processing the pre-call message or the peer device does not support the pre-negotiation method, the call initiating end VoIP device A will hang up the local call after 5 seconds, and the user processing module will display the new call status to the user in the form of images and sounds;

[0102] Step 5: The event processing module of the called device B stores the call event in the call list;

[0103] The event processing module packages the relevant information of this call into a call event, and stores it in a linked list after sorting it according to factors such as time and call priority in other business information for subsequent use.

[0104] Step 6: The event processing module of the called device B transmits the call event to the user interface module to update the call status;

[0105] The user interface module reads the relevant information in the call event, renders a prompt window of the call information to the screen of device B, and calls the speaker of the device to play the specified audio at the set volume.

[0106] Prompt window: reads the device configuration information, and displays the corresponding color and background image window corresponding to the message priority value in other business information;

[0107] Specified audio: Plays the specified music file at the specified volume according to the device configuration information and the message priority value in other business information.

[0108] Step 7: User B0 updates the call information through the user interface module and chooses to accept the pre-call, reject the pre-call or transfer the pre-call;

[0109] Step 8: The user input module of the called device B receives a key event, and the event processing module processes the key event.

[0110] If the user chooses to accept the pre-call, the called device B calls the call control module to actively initiate a standard SIP call to the peer A, and the peer A will automatically answer the call to user A0, causing the caller to be connected;

[0111] If user B0 chooses to reject the pre-call, the called device B sends a hang-up pre-call message to the peer device indicating that the call is actively rejected;

[0112] If user B0 selects the transfer pre-call, the called device sends a transfer pre-call message to the opposite device, indicating which type of call should be used to initiate the call again to the designated number.

[0113] 1) Accept pre-call;

[0114] The user interface module transmits the selection to the call control module, and actively initiates a standard SIP call to the pre-call initiating device A. After the pre-call initiating device A automatically answers the call, the two devices enter the standard SIP call process;

[0115] 2) Reject pre-call;

[0116] The user interface module transmits the selection to the SMS control module, and sends a pre-negotiation SMS message to the pre-call initiating device A indicating that the called party rejects the pre-call, and the pre-call process ends on both devices;

[0117] 3) Transfer pre-call.

[0118] The user interface module will select and transmit the transmission to the SMS control module, which will send a pre-negotiation SMS to transfer the pre-call to the pre-call initiating device A. The pre-call initiating device will extract the peer VoIP device number C and the call method type in the pre-call SMS protocol body, and repeat step three to initiate a standard SIP call or pre-call.

Claims

1. A method for expanding the concurrent incoming call volume of a VoIP device based on SIP messages, characterized in that: The specific steps are as follows: Step 1: For the VoIP device A that is to initiate a call, user A0 sets the number and call method type of the other party's VoIP device B to the function button DSS Key of device A; Each VoIP device includes a user input module, a text message control module, a call control module, an event processing module, and a user interface module; The call method types include: standard SIP call type, or call type based on SIP message expansion of the concurrent incoming call volume of VoIP devices; Step 2: When user A0 presses the function key DSS Key, device A determines whether to use the standard SIP call process according to the configured call method type. If yes, the call control module of device A is called to call the number of device B; otherwise, it goes to step 3; Step 3: Device A selects the call type based on SIP message expansion of concurrent incoming calls of VoIP devices, that is, calls the sending interface of the SMS control module to send a pre-call SMS to the number of device B. At this time, device B allows multiple devices to make concurrent incoming calls; Step 4: The SMS control module of device B receives the pre-call SMS and transmits it to its own event processing module; the event processing module calls the SMS control module to send a response pre-call message to device A, indicating that the call is received; Step 5: The event processing module of device B stores the call event corresponding to the pre-call SMS in the call list, and transmits it to the user interface module to update the call status, that is, display an incoming call reminder in the same style as a standard SIP call; Step 6: User B0 presses the physical button of device B or the virtual button on the screen to select accept, reject or transfer the pre-call; Step 7: The user input module of device B receives the key event and transmits it to the event processing module for key event processing: If user B0 chooses to accept the pre-call, device B calls the call control module to actively initiate a standard SIP call to device A, that is, the standard SIP call that should have been initiated by device A to device B is postponed, and device B becomes the call initiator; at the same time, device A will automatically answer the call to user A0, causing the caller to be connected; If user B0 chooses to reject the pre-call, device B sends a hang-up pre-call message to the peer device A indicating that the call is actively rejected; If user B0 selects transfer pre-call, user B0 should enter the number of device C for transfer pre-call and select the call type. Device B sends a transfer pre-call message to the other device A, indicating that a call is initiated again to device C according to the selected call type.

2. A method for expanding the number of concurrent incoming calls of a VoIP device based on SIP messages as claimed in claim 1, characterized in that: In the step 1, the user input module is responsible for receiving key events of physical keys and virtual keys on the touch screen, and distributing them to the event processing module; The SMS control module is responsible for sending and receiving SMS messages and distributing SMS events to the event processing module; The call control module is responsible for initiating, hanging up and transferring operations, and distributing call events to the event processing module; The event processing module first receives the SMS message sent by the other party, responds to the other party to indicate that the call has been received and stored locally, then the local call list changes, thereby triggering a change in the user interface; finally, when the user presses a button, the user interface module calls the event processing module to continue processing according to the user's selection; The user interface module is responsible for presenting events to the user in the form of screen images and speaker sounds.

3. A method for expanding the concurrent incoming call volume of a VoIP device based on SIP messages as claimed in claim 1, characterized in that: In the step 3, the pre-call SMS includes a protocol header and a protocol body; The From field in the protocol header contains the number of device A; the To field contains the number of device B; The protocol body contains: The cid field indicates the pre-call ID, which identifies different pre-calls of the VoIP device; The event field indicates the call event operation to be performed on the call, including initiating pre-call invite, responding to pre-call invite back, calling party hanging up pre-call end, called party hanging up pre-call know, and transferring pre-call unattended; Other business information: other information required by the actual business, including protocol version number version, message priority callType, device name callUser, device ID, device IP address, device MAC address and device location information.

4. A method for expanding the concurrent incoming call volume of a VoIP device based on SIP messages as claimed in claim 1, characterized in that: In step 7, the hang-up pre-call message body includes the following fields: endUser field: the number of device B; endType field: reason for hang-up; 0 means device A received the hang-up from device B, 1 means the hang-up was caused by device B not answering the call due to timeout, 2 means device A actively hung up, and 3 means the hang-up was caused by call priority adjustment.

5. A method for expanding the concurrent incoming call volume of a VoIP device based on SIP messages as claimed in claim 1, characterized in that: In step 7, the transfer pre-call message body includes the following fields: tranferTargetUser field: the number of device C; tranferTargetDevice field: call type; tranferTargetIp field: IP address of device C.

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