Abstract:
A structure for encapsulating a message to be exchanged between an IP phone and an entity within an Ethernet-based PBX, comprising a Protocol Header and an IP Message body wherein the Protocol Header includes an indication of Protocol Type for denoting whether the message is an IP message or an encapsulated non-IP message, Device Number for denoting by means of a MAC (Media Access Control) an address for said entity within said PBX to which said message is to be transmitted or from which said message is to be received, and Message Type for identifying the type of message contained in the IP Message Body.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to Internet Protocol (IP) telephony, and more particularly to a method of controlling IP telephones within a LAN-implemented or Ethernet PBX using a specialized messaging protocol.  
         BACKGROUND OF THE INVENTION  
         [0002]    With the increasing pervasiveness of the Internet, Voice-over-IP (VoIP) is rapidly displacing additional TDM (Time Division Multiplexing) voice communications. In order to establish communications with Ethernet PBXs, an IP transport control messaging protocol is required to be established between the phone and PBX system.  
         SUMMARY OF THE INVENTION  
         [0003]    According to the present invention, a byte oriented and easily adaptable messaging protocol is provided for communications between IP telephones and Ethernet voice-LAN systems. The messages are required to implement essential tasks such as IP phone registration with the system upon phone power up or reset, the application of device tones to IP phones, and connection control for establishing full-duplex voice paths between IP phones. The messaging protocol of the invention also supports additional administrative and telephony functions.  
           [0004]    The general message template consists of a Protocol Header and an IP Message body. The Protocol Header, in turn, includes an indication of the Protocol Type, Device Number and Message Type. The Device Number identifies the entity sharing the same MAC (Media Access Control) address that the messages are destined to or coming from, Message Type identifies the type of message contained in the IP Message Body. The protocol Type denotes whether the message is an IP message (e.g. Mitel proprietary Minet IP message) or an encapsulated non-IP message (e.g. Mitel proprietary Minet (MTS 22) message). The Minet (MTS 22) messaging protocol is implemented in Mitel PBX models SX50, SX200, SX2000, IPERA 2000 for communicating With associated telephones such as Mitel models SS4001, SS4015, SS4025, SS4150, SS4015IP and SS4025IP. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    A preferred embodiment of the present invention will now be described more fully with reference to the accompanying drawings in which:  
         [0006]    [0006]FIG. 1 is a message flow diagram showing registration of an IP phone with an Ethernet PBX; and  
         [0007]    [0007]FIG. 2 is a message flow diagram showing the establishment of a full duplex voice path between a pair of IP phones. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0008]    The messaging protocol and collection of specific messages of the present invention have particular application to the assignee&#39;s legacy mix of assembly and higher level languages. Consequently, reference to Minet and MinetIP messages occur throughout this disclosure to indicate the preferred embodiment and best mode implementation of the invention.  
         [0009]    The Minet messaging extensions are structure based and are long word aligned, the result of which is that a user with a packet Sniffer will detect filler bytes in between short and long words.  
         [0010]    In order to control a Mitel IP Phone, both Minet and Minet IP messages are required. A common message wrapper is defined to house the messages. The general message template consists of a Protocol Header and a Minet IP Message body that may or may not consist of an MTS22 Minet payload “wrapper”.  
         [0011]    Protocol Header:  
                                                       ProtoType:   4 bytes, unsigned long integer, Protocol Type           devNum:   4 bytes, unsigned long integer, Device Number           msgType:   4 bytes, unsigned long integer, Message Type                      
 
         [0012]    The message body follows the Protocol Header as shown in the structure below:  
                                                                                                                           typedef struct_IPSP_MSG {                PROTOCOL_HEADER_MSG hdr;           union_msg {                MINET_WRAPPER_MSG   MWM;           DEVICE_REGISTRATION_MSG   DRM;           DEVICE_REGISTRATION_ACK_MSG   DRAM;                DEVICE_UNREGISTER_MSG   DUM;                DEVICE_UNREGISTER_ACK_MSG   DUAM;           OPEN_RX_STREAM_REQUEST_MSG   ORSRM;           OPEN_RX_STREAM_ACK_MSG   ORSAM;           CLOSE_RX_STREAM_REQUEST_MSG   CRSRM;           CLOSE_RX_STREAM_ACK_MSG   CRSAM;           OPEN_TX_STREAM_REQUEST_MSG   OTSRM;           OPEN_TX_STREAM_ACK_MSG   OTSAM:           CLOSE_TX_STREAM_REQUEST_MSG   CTSRM;           CLOSE_TX_STREAM_ACK_MSG   CTSAM;           APPLY_TONE_REQUEST_MSG   ATRM;           REMOVE_TONE_REQUEST_MSG   RTRM;           DEVICE_PING_REQUEST_MSG   DPRM;           DEVICE_PING_ACK_MSG   DPAM;           DEVICE_IP_UPDATE_REQUEST_MSG   DIURM;           DEVICE_IF_UPDATE_ACK_MSG   DIUAM;                } msg;            } IPSP_MSG;       typedef struct {                protocolType_t   protoType;           deviceNumber_t   devNum;           messageType_t   msgType;            } PROTOCOL_HEADER_MSG:                  
 
         [0013]    Protocol Type:  
                                                       INVALID_PROTOCOL_TYPE   0x00000000           MINET_MTS22   0x00000001           MITEL_INTERNAL   0x00000002                      
 
         [0014]    The Protocol Type denotes whether the message is a Minet IP message or an encapsulated Minet (MTS 22) message.  
         [0015]    Device Number:  
                                                       Phone   0x00000000           Device #1 i.e. PKM   0x00000001           Device #2   0x00000002           ...   ...           Device #n   0x0000000n                      
 
         [0016]    The Device Number denotes which entity sharing the same MAC address the messages are destined to or coming from.  
         [0017]    Message Type:  
                                                       INVALID_MESSAGE_TYPE   0x00000000           DEVICE_REGISTRATION   0x00000001           DEVICE_REGISTRATION_ACK   0x00000002           DEVICE_REGISTRATION   0x00000003           DEVICE_DEREGISTRATION_ACK   0x00000004           OPEN_RX_STREAM   0x00000005           OPEN_RX_STREAM_ACK   0x00000006           CLOSE_RX_STREAM   0x00000007           CLOSE_RX_STREAM_ACK   0x00000008           OPEN_TX_STREAM   0x00000009           OPEN_TX_STREAM_ACK   0x0000000a           CLOSE_TX_STREAM   0x0000000b           CLOSE_TX_STREAM_ACK   0x0000000c           MINET_WRAPPER   0x0000000d           APPLY_TONE   0x0000000e           REMOVE_TONE   0x0000000f           DEVICE_PING   0x00000010           DEVICE_PING_ACK   0x00000011           DEVICE_IP_UPDATE   0x00000012           DEVICE_IP_UPDATE_ACK   0x00000013           INVALID_MSG_TYPE   0x00000014                      
 
         [0018]    Minet IP Registration Sequence  
         [0019]    As shown in FIG. 1, when the IP Phone  1  powers up or resets, it must register with the PBX  3 . The phone  1  originates a Registration Request and receives a Registration Acknowledgement in return. The PBX  3  checks the Device ID of the phone (its MAC address) and verifies if it has it in the CDE database. If not, the system sends the phone  1  an MTS22 Minet for PIN Request. The phone buffers the key entries and sends up one message containing the PIN Reply (also an MTS22 Minet message).  
         [0020]    The following messages are used to register and de-register the phone  1  with the PBX  3 :  
         [0021]    Device Registration request message sent from the IP Phone  
         [0022]    ProtoType=MITEL_INTERNAL  
         [0023]    DevNum=N where N=0, 1, 2, . . . n  
         [0024]    msgType=DEVICE_REGISTRATION  
         [0025]    DEVICE_REGISTRATION_MSG  
                                       devId:   6 unsigned byte array        mac_addr[6]   MAC address of Phone.           Note that due to long word alignment, there           may be 2 bytes of filler between the MAC           address and the next defined field.       devType:   4 bytes, unsigned long integer, Type of device           (i.e., SET, PKM, . . .)       devNumber:   4 bytes, unsigned long integer, Number of           device: Master, Slave01, Slave02, . . .       ipAddress:   structure        ip_addr   4 bytes, unsigned long integer, IP Address           of device,        ip_port   2 bytes, unsigned short integer, port number           of protocol medium.           Note that due to long word alignment, there           may be two bytes of filler between this           field and the next.       DeviceCaps:   structure: Functionality supported by this           device        strmCodec   4 bytes, unsigned long integer (bitmap),           System selected CODEC to use. Multiple           CODECs may be logically Ored into this           field.       numTxStreams:   4 bytes, unsigned long integer, Number of           Tx streams supported by the device       numRxStreams:   4 bytes unsigned long integer, Number of           Rx streams supported by the device       prefStrmFrameSizeInMS:   4 bytes, unsigned long integer, Devices           preferred frame size for streams (in ms)       silenceSupp:   4 bytes, unsigned long integer:           silenceSupp = 0: device does not support           silence suppression           silenceSupp = 1: device supports silence           suppression       toneGeneration:   4 bytes, unsigned long integer:           toneGeneration = 0: device does not support           local tone generation.           toneGeneration = 1: device supports local tone           generation                  
 
         [0026]    Device Registration request Acknowledgment message sent from system  
         [0027]    ProtoType=MITEL_INTERNAL  
         [0028]    DevNum=N where N=0, 1, 2, . . . n  
         [0029]    msgType=DEVICE_REGISTRATION_ACK  
         [0030]    DEVICE_REGISTRATION_ACK_MSG  
                                       reqStatus:   4 bytes, unsigned long integer, Success/Failure Result of the           request       sysToken:   4 bytes, unsigned long integer, System defined “token” that           must be passed back with any follow up message related           to this message i.e. Device Unregister.                  
 
         [0031]    Device De-Registration Request message sent from IP Phone.  
         [0032]    ProtoType=MITEL_INTERNAL  
         [0033]    DevNum=N where N=0, 1, 2 . . . n  
         [0034]    msgType=DEVICE_DEREGISTRATION  
         [0035]    Note that the IP Phone will not unregister itself, but rather an associated device such as a PKM may be removed and hence deregistered.  
         [0036]    DEVICE_UNREGISTER_MSG  
                                       sysToken:   4 bytes, unsigned long integer, System defined “token”           taken from the Registration Acknowledgment from the           system.       devType:   4 bytes, unsigned long integer, Type of device (i.e., SET,           PKM, etc. . .)       devNumber:   4 bytes, unsigned long integer, Number of device: Master,           Slave01, Slave02, . . .       ipAddress:   structure        ip_addr   4 bytes, unsigned long integer, IP Address of device,        ip_port   2 bytes, unsigned short integer, port number of protocol           medium.                  
 
         [0037]    Device De-Registration Acknowledgment message sent from system  
         [0038]    ProtoType=MITEL_INTERNAL  
         [0039]    DevNum=N where N=0, 1, 2 . . . n  
         [0040]    msgType=DEVICE_DEREGISTRATION_ACK  
         [0041]    DEVICE_UNREGISTER_ACK_MSG  
         [0042]    reqStatus: 4 bytes, unsigned long integer, Success/Failure Result of the request  
         [0043]    devNumber: 4 bytes, unsigned long integer, Number of device: Master, Slave01, Slave02, . . .  
       DETAILED DESCRIPTION OF REGISTRATION PARAMETERS  
       [0044]    devType:  
                                                       INVALID_DEVICE_TYPE   0x00000000           IP_SUPERSET4001   0x00000001           IP_SUPERSET4015   0x0000009f           IP_SUPERSET4025   0x000000a0           IP_SUPERSET4150   0x00000004           PKM   0x00000005           AIM   0x00000006           SYMBOL_PROXY   0x00000007           SYMBOL_SET   0x00000008           TELEWORKER_PROXY   0x00000009           TELEWORKER_SET   0x0000000a           E2T_PROXY   0x0000000b           MAX_DEVICE_TYPE   0x0000000c                      
 
         [0045]    devNumbers:  
         [0046]    MASTER_DEVICE 0×00000000  
         [0047]    Were Set=0, and any attached devices will be numbered MASTER_DEVICE+n where n&gt;=1  
         [0048]    reqStatus (Success/failure codes):  
                                                       MTL_SUCCESS   0x00000000           MTL_FAILURE   0x00000001           MTL_NO_PERMISSIONS   0x00000002           MTL_NO_RESOURCES   0x00000003           MTL_INVALID_DEVICE   0x00000004           MTL_INVALID_REQUEST   0x00000005                      
 
         [0049]    devCodecs bitmap:  
                                           NO_CODEC_SUPPORT   0x0   (000 00000000)       G711_ULAW64   0x1   (000 00000001)       G711_ALAW64   0x2   (000 00000010)       G728   0x4   (000 00000100)       G729   0x8   (000 00001000)       G729_ANNEXB   0x10   (000 00010000)       G729_ANNEXA_w_ANNEXB   0x20   (000 00100000)       G723   0x40   (000 01000000)       G7231_ANNEXC   0x80   (000 10000000)       Placeholder1   0x100   (001 00000000)       Placeholder2   0x200   (010 00000000)       Placeholder3   0x400   (100 00000000)       INVALID_CODEC   0x7FF   (111 11111111)                  
 
         [0050]    For system maintenance purposes, it is desirable to provide a mechanism for testing the presence of an operating IP phone  1  in the system by generation of echo (PING) messages to the phone  1 . The following messages are used to implement this functionality:  
         [0051]    Device ICMP Echo (Ping) request to the phone  
         [0052]    ProtoType=MITEL_INTERNAL  
         [0053]    DevNum=N where N=0, 1, 2, . . . n  
         [0054]    msgType=DEVICE_PING  
         [0055]    DEVICE_PING_REQUEST_MSG  
                                                               hostIpAddress:   structure                ip_addr   4 bytes, unsigned long integer, IP Address of device to               PING,           ip_port   2 bytes, unsigned short integer, port number is               IGNORED.               Note that due to long word alignment, there may be two               bytes of filler following this field.            numRequests   4 bytes, unsigned long integer, Number of ping requests           to send       pktSize   4 bytes, unsigned long integer, Size of data packet to           send (in bytes)       pktDelay   4 bytes, unsigned long integer, Inter packet delay in           Milliseconds       timeOut   4 bytes, unsigned long integer, Ping request timeout in           Milliseconds       qosLevel   4 bytes, unsigned long integer, QOS level requested                  
 
         [0056]    Device ICMP Echo (Ping) results sent from the phone to the system  
         [0057]    ProtoType=MITEL_INTERNAL  
         [0058]    DevNum=N where N=0, 1, 2, . . . n  
         [0059]    msgType=DEVICE_PING_ACK  
         [0060]    DEVICE_PING_ACK_MSG  
                                                               hostIpAddress:   structure                ip_addr   4 bytes, unsigned long integer, IP Address of device that               was PINGed,           ip_port   2 bytes, unsigned short integer, port number is               IGNORED.               Note that due to long word alignment, there may be two               bytes of filler following this field.            pktsSent   4 bytes, unsigned long integer, Number of ICMP echo requests sent       pktsRecv   4 bytes, unsigned long integer, Number of ICMP echo replys received       pktLoss   4 bytes, unsigned long integer, Percentage of packets lost       rttMax   4 bytes, unsigned long integer, Maximum round trip time (in milliseconds)       rttMin   4 bytes, unsigned long integer, Minimum round trip time (in milliseconds)       rttAvg   4 bytes, unsigned long integer, Average round trip time (in milliseconds)                  
 
       DETAILED DESCRIPTION OF PING PARAMETERS  
       [0061]    qosLevel:  
                                                       QOS_LEVEL_NONE   0×ffffffff           QOS_LEVEL_0   0×00000000           QOS_LEVEL_1   0×00000001           QOS_LEVEL_2   0×00000002           QOS_LEVEL_3   0×00000003           QOS_LEVEL_4   0×00000004           QOS_LEVEL_5   0×00000005           QOS_LEVEL_6   0×00000006           QOS_LEVEL_7   0×00000007                      
 
         [0062]    Once the IP phone  1  has been registered with PBX  3 , and in response to a user going off-hook, the PBX  3  is required to provide tones to phone in order to provide the use with an indication of the call state (e.g. dial tone, busy, etc.) The following messages are used for the provisioning of device tones to the phone  1 :  
         [0063]    Apply Tone device tone generation request message to the phone:  
         [0064]    ProtoType=MITEL_INTERNAL  
         [0065]    DevNum=N where N=0, 1, 2, . . . n  
         [0066]    msgType=APPLY_TONE  
         [0067]    APPLY_TONE_REQUEST_MSG  
                                                                         sysToken:   4 bytes, unsigned long integer, System defined “token” that must           be passed back with the Remove Tone request.       sysStrmID:   4 bytes, unsigned long integer, System provided stream ID which           maps the voice streams to legacy B channels            tone [MAX_COMPLEX_TONE]:   array of tone structures of frequencies the DSP is           to play                on_T1   2 bytes, unsigned long integer, Duration in ms of 1st ON period           off_T1   2 bytes, unsigned long integer, Duration in ms of 1st OFF period           on_T2   2 bytes, unsigned long integer, Duration in ms of 2nd ON period           off_T2   2 bytes, unsigned long integer, Duration in ms of 2nd OFF period               num_cycles 2 bytes, unsigned long integer, Number of times to               repeat the ON/OFF sequence           tail   2 bytes, unsigned long integer, After num_cycles, 0 = leave tone               off, 1 = on           freq_1   2 bytes, unsigned long integer, 1st frequency component in Hz           freq_2   2 bytes, unsigned long integer, 2nd frequency component in Hz           level_1   2 bytes, unsigned long integer, 1st frequency signal level           level_2   2 bytes, unsigned long integer, 2nd frequency signal level           action   2 bytes, unsigned long integer, indicates the action to take on               completion of the tone. The actions are either to continue to the               next tone descriptor, reconnect to the audio stream, or just stop.               Note that due to long word alignment, there may be 2 bytes of filler               following this field.            toneId:   4 bytes, unsigned long integer, System Tone ID of the tone           being applied       inject;   4 bytes, unsigned long integer, specify whether to inject the           tone on top of voice or not. This is unused by the phone           since the tone will always take precedence over voice.                  
 
         [0068]    Remove Tone device tone generation request message to the phone  
         [0069]    ProtoType=MITEL_INTERNAL  
         [0070]    DevNum=N where N=0, 1, 2, . . . n  
         [0071]    msgType=REMOVE_TONE  
       REMOVE_TONE_REQUEST_MSG  
       [0072]    [0072]                                                               sysToken:   4 bytes, unsigned long integer, System defined “token” that was           given with the Apply Tone request.       sysStrmID:   4 bytes, unsigned long integer, System provided stream ID which           maps the voice streams to legacy B channels            tone[MAX_COMPLEX_TONE]:   array of tone structures of frequencies the DSP           was playing out to the CODEC that it is to           remove. Note that this is IGNORED BY IP           PHONE                on_T1   2 bytes, unsigned long integer, Duration in ms of 1st ON period           off_T1   2 bytes, unsigned long integer, Duration in ms of 1st OFF period           on_T2   2 bytes, unsigned long integer, Duration in ms of 2nd ON period           off_T2   2 bytes, unsigned long integer, Duration in ms of 2nd OFF period           num_cycles   2 bytes, unsigned long integer, Number of times to repeat the               ON/OFF sequence           tail   2 bytes, unsigned long integer, After num_cycles, 0 = leave tone               off, 1 = on           freq_1   2 bytes, unsigned long integer, 1st frequency component in Hz           freq_2   2 bytes, unsigned long integer, 2nd frequency component in Hz           level_1   2 bytes, unsigned long integer, 1st frequency signal level           level_2   2 bytes, unsigned long integer, 2nd frequency signal level           action   2 bytes, unsigned long integer, indicates the action to take on               completion of the tone. The actions are either to continue to the               next tone descriptor, reconnect to the audio stream, or just stop.                        
       DETAILED DESCRIPTION OF TONE PARAMETERS  
       [0073]    inject:  
                                                       NOT_INJECTED   0×00000000           NORMAL_INJECTION   0×00000001           MAX_TONE_INJECT   0×00000002           MAX_COMPLEX_TONE   3           action:           NEXT   0×00000000           RECONNECT   0×00000001           STOP   0×00000002                      
 
         [0074]    [0074]FIG. 2 is a message flow diagram showing the messages required to establish communications between a pair of IP phones  1 A and  1 B via an IP Phone Service Provider  5  of PBX  3 . The following messages are required to implement such communications:  
         [0075]    Open Receive Stream Request to the phone:  
         [0076]    ProtoType=MITEL_INTERNAL  
         [0077]    DevNum=N where N=0, 1, 2, . . . n  
         [0078]    msgType=OPEN_RX_STREAM  
         [0079]    OPEN_RX_STREAM_REQUEST_MSG  
                                                                                       sysToken:   4 bytes, unsigned long integer, System defined “token”           that must be passed back with the corresponding Close           Receive Stream Request.       sysStrmID:   4 bytes, unsigned long integer, System provided stream           ID. This field denotes the B channel the connection           should assume.       strmCodec   4 bytes, unsigned long integer (bitmap), System selected           CODEC to use. Multiple CODECs may be logically Ored           into this field.       strmFrameSizeInMS   4 bytes, unsigned long integer, Preferred CODEC frame           size for the RX stream (in milliseconds)       isMulticast   4 bytes, unsigned long integer           isMulticast = 0: no Multicast, ignore mcIpAddress.           isMulticast = 1: the steam must be bound to the           mcIpAddress Multicast address.       mcIpAdress:   structure                ip_addr   4 bytes, unsigned long integer, Multicast address to               receive on           ip_port   2 bytes, unsigned short integer, Multicast port number to               receive on.               Note that due to long word alignment, there may be two               bytes of filler following this field.            SrcIpAddress:   structure: IGNORED BY THE IP PHONE.                ip_addr   4 bytes, unsigned long integer, The ip address of the               device that will be transmitting to the phone.           ip_port   2 bytes, unsigned short integer, port number used by the               device that will be transmitting to the phone.               Note that due to long word alignment, there may be two               bytes of filler following this field.            noSilence   4 bytes, unsigned long integer,           noSilence = 0: no silence suppression applied by the           transmitting end           noSilence = 1: silence suppression is being applied by           the transmitting end                  
 
         [0080]    Open Receive Stream Acknowledgement from the IP Phone to the system:  
         [0081]    ProtoType=MITEL_INTERNAL  
         [0082]    DevNum=N where N=0, 1, 2, . . . n  
         [0083]    msgType=OPEN_RX_STREAM_ACK  
         [0084]    OPEN_RX_STREAM_ACK_MSG  
                                                     reqStatus:   4 bytes, unsigned long integer, Success/Failure Result           of the request       sysToken:   4 bytes, unsigned long integer, System provided           “token” from the request message       rxConnectionID:   4 bytes, unsigned long integer, Device selected           stream/connection identifier. The IP Phone returns the           value of the sysStrmID (B channel) in this field       rxStrmIpAddress:   structure                ip_addr   4 bytes, unsigned long integer, The local ip address               that will receive stream           ip_port   2 bytes, unsigned short integer, local port number to               receive on.                      
 
         [0085]    Close Receive Stream Request from the system to the IP Phone:  
         [0086]    ProtoType=MITEL_INTERNAL  
         [0087]    DevNum=N where N=0, 1, 2, . . . n  
         [0088]    msgType=CLOSE_RX_STREAM  
         [0089]    CLOSE_RX_STREAM_REQUEST_MSG  
                                       sysToken:   4 bytes, unsigned long integer, System defined “token” that           was given with the Open Receive Stream Request.       sysStrmID:   4 bytes, unsigned long integer, Id of RX stream/connection           (B channel) to close                  
 
         [0090]    Close Receive Stream Acknowledgement from the IP Phone:  
         [0091]    ProtoType=MITEL_INTERNAL  
         [0092]    DevNum=N where N=0, 1, 2, . . . n  
         [0093]    msgType=CLOSE_RX_STREAM_ACK  
         [0094]    CLOSE_RX_STREAM_ACK_MSG  
                                                     reqStatus:   4 bytes, unsigned long integer, Success/Failure           Result of the request       sysToken:   4 bytes, unsigned long integer, System           provided “token” from the request message       rxStrmStats:   structure: Stream statistics upon closure                Packets.recv   4 bytes, unsigned long integer, number of RTP               packets received           Bytes.recv   4 bytes, unsigned long integer, number of voice               octets received           Errors.rxStream   4 bytes, unsigned long integer, number of               RTP errors received           Jitter.rxStream   4 bytes, unsigned long integer, estimate of               average jitter over duration of call           Duration.rxStream   4 bytes, unsigned long integer, duration of call               in seconds           IpAddress.src:   structure           ip_addr   4 bytes, unsigned long integer, the               local ip address           ip_port   2 bytes, unsigned short integer, the local               port number.                      
 
         [0095]    Open Transmit Stream Request to the IP Phone:  
         [0096]    ProtoType=MITEL_INTERNAL  
         [0097]    DevNum=N where N=0, 1, 2, . . . n  
         [0098]    msgType=OPEN_TX_STREAM  
         [0099]    OPEN_TX_STREAM_REQUEST_MSG  
                                                               sysToken:   4 bytes, unsigned long integer, System defined “token”           that must be passed back with the corresponding Close           Transmit Stream Request.       sysStrmID:   4 bytes, unsigned long integer, System provided stream           ID. This field denotes the B channel the connection           should assume.       strmCodec   4 bytes, unsigned long integer (bitmap), System selected           CODEC to use, Multiple CODECs may be logically Ored           into this field.       strmFrameSizeInMS   4 bytes, unsigned long integer, Preferred CODEC frame           size for the TX stream (in milliseconds)       destStrmIpAddress:   structure                ip_addr   4 bytes, unsigned long integer, The IP address of the               device to transmit to.           ip_port   2 bytes, unsigned short integer, port number used by the               device that will be transmitting to the phone.               Note that due to long word alignment, there may be two               bytes of filler following this field.            qosLevel   4 bytes, unsigned long integer, QoS level requested. If           0×fffffff, then no 802.1Q tag, else if 0-7, assume 802.1Q           tag and set priority field to the qosLevel       noSilence   4 bytes, unsigned long integer           noSilence = 0: disable silence suppression on the Tx           stream           noSilence = 1: enable silence suppression on the Tx stream                  
 
         [0100]    Open Transmit Stream Acknowledgement from the IP Phone:  
         [0101]    ProtoType=MITEL_INTERNAL  
         [0102]    DevNum=N where N=0, 1, 2, . . . n  
         [0103]    msgType=OPEN_TX_STREAM_ACK  
         [0104]    OPEN_TX_STREAM_ACK_MSG  
                                                     reqStatus:   4 bytes, unsigned long integer, Success/Failure Result           of the request       sysToken:   4 bytes, unsigned long integer, System provided           “token” from the request message       txConnectionID:   4 bytes, unsigned long integer, Device selected           stream/connection identifier. The IP Phone returns the           value of the sysStrmID (B channel) in this field       txStrmIpAddress:   structure                ip_addr   4 bytes, unsigned long integer, The local IP address               that will transmit stream           ip_port   2 bytes, unsigned short integer, local port number the               phone will transmit from.                      
 
         [0105]    Close Transmit Stream Request to the IP Phone  
         [0106]    ProtoType=MITEL_INTERNAL  
         [0107]    DevNum=N where N=0, 1, 2, . . . n  
         [0108]    msgType=CLOSE_TX_STREAM  
         [0109]    CLOSE_TX_STREAM_REQUEST_MSG  
                                       sysToken:   4 bytes, unsigned long integer, System defined “token”           that was given with the Open Transmit Stream Request.       sysStrmID:   4 bytes, unsigned long integer, Id of TX stream/connection           (B channel) to close                  
 
         [0110]    Close Transmit Stream Acknowledgement from the IP Phone:  
         [0111]    ProtoType=MITEL_INTERNAL  
         [0112]    DevNum=N where N=0, 1, 2, . . . n  
         [0113]    msgType=CLOSE_TX_STREAM_ACK  
         [0114]    CLOSE_TX_STREAM_ACK_MSG  
                                                                   reqStatus:   4 bytes, unsigned long integer, Success/Failure Result of           the request       sysToken:   4 bytes, unsigned long integer, System provided “token”           from the request message       txStrmStats:   structure: Stream statistics upon closure                Packets.sent   4 bytes, unsigned long integer, number of RTP packets               sent           Bytes.sent   4 bytes, unsigned long integer, number of voice octets               sent           Errors.txStream   4 bytes, unsigned long integer, number of RTP errors sent.               IGNORE, NOT RELEVENT           Jitter.txStream   4 bytes, unsigned long integer, estimate of average jitter               over duration of call IGNORE, NOT RELEVENT           Duration.txStream   4 bytes, unsigned long integer, duration of call in seconds           IpAddress.dest:   structure                ip_addr   4 bytes, unsigned long integer, the local IP address used               to Tx           ip_port   2 bytes, unsigned short integer, the local port number               used to Tx.                      
 
       DETAILED DESCRIPTION OF CONNECTION PARAMETERS  
       [0115]    reqStatus (Success/failure codes):  
                                                       MTL_SUCCESS   0×00000000           MTL_FAILURE   0×00000001           MTL_NO_PERMISSIONS   0×00000002           MTL_NO_RESOURCES   0×00000003           MTL_INVALID_DEVICE   0×00000004           MTL_INVALID_REQUEST   0×00000005                      
 
         [0116]    SysStrmID:  
         [0117]    IP Set Stream IDs: (NOTE: TX is always even) used for sysStrmID of Tx &amp; Rx connect requests  
                                                       STREAM_ID_IP_SET_TX_1   0×00000000 // B1 TX           STREAM_ID_IP_SET_RX_1   0×00000001 // B1 RX           STREAM_ID_IP_SET_TX_2   0×00000002 // B2 TX           STREAM_ID_IP_SET_RX_2   0×00000003 // B2 RX                      
 
         [0118]    devCodecs bitmap:  
                                                           NO_CODEC_SUPPORT   0×0   (000 00000000)           G711_ULAW64   0×1   (000 00000001)           G711_ALAW64   0×2   (000 00000010)           G728   0×4   (000 00000100)           G729   0×8   (000 00001000)           G729_ANNEXB   0×10   (000 00010000)           G729_ANNEXA_w_ANNEXB   0×20   (000 00100000)           G723   0×40   (000 01000000)           G7231_ANNEXC   0×80   (000 10000000)           Placeholder1   0×100   (001 00000000)           Placeholder2   0×200   (010 00000000)           Placeholder3   0×400   (100 00000000)           INVALID_CODEC   0×7FF   (111 11111111)                      
 
         [0119]    qosLevel:  
                                                       QOS_LEVEL_NONE   0×ffffffff           QOS_LEVEL_0   0×00000000           QOS_LEVEL_1   0×00000001           QOS_LEVEL_2   0×00000002           QOS_LEVEL_3   0×00000003           QOS_LEVEL_4   0×00000004           QOS_LEVEL_5   0×00000005           QOS_LEVEL_6   0×00000006           QOS_LEVEL_7   0×00000007                      
 
         [0120]    One important system administration requirement for IP phone systems is to provide a mechanism for updating the IP address for a device (e.g. an IP phone) connected to the Ethernet PBX  3 . The following messages are used to implement this functionality:  
         [0121]    Device IP address update request to the phone:  
         [0122]    ProtoType=MITEL_INTERNAL  
         [0123]    DevNum=N where N=0, 1, 2, . . . n  
         [0124]    msgType=DEVICE_IP_UPDATE  
         [0125]    DEVICE_IP_UPDATE_REQUEST_MSG  
                                                                             devNumber   4 bytes, unsigned long integer, Number at device:           Master, Slave01, Slave02, . . .       oldIpAddress:   structure                ip_addr   4 bytes, unsigned long integer, old IP Address of device           ip_port   2 bytes, unsigned short integer,               old port number of device               Note that due to long word alignment, there may be two               bytes of filler following this field.            newIpAddress:   structure                ip_addr   4 bytes, unsigned long integer, new IP Address of device           ip_port   2 bytes, unsigned short integer, new port number of               device                      
 
         [0126]    Device IP address update acknowledgement from the phone:  
         [0127]    ProtoType=MITEL_INTERNAL  
         [0128]    DevNum=N where N=0, 1, 2, . . . n  
         [0129]    msgType=DEVICE_IP_UPDATE_ACK  
         [0130]    DEVICE_IP_UPDATE_ACK_MSG  
         [0131]    reqStatus: 4 bytes, unsigned long integer, Success/Failure Result of the request  
       PARAMETERS DESCRIPTION  
       [0132]    reqStatus (Success/failure codes):  
                                                       MTL_SUCCESS   0×00000000           MTL_FAILURE   0×00000001           MTL_NO_PERMISSIONS   0×00000002           MTL_NO_RESOURCES   0×00000003           MTL_INVALID_DEVICE   0×00000004           MTL_INVALID_REQUEST   0×00000005                      
 
         [0133]    devNumbers:  
         [0134]    MASTER_DEVICE 0×00000000  
         [0135]    Where Set=0, and any attached devices will be numbered MASTER_DEVICE+n where n&gt;=1  
         [0136]    Finally, as indicated above, the messaging protocol of the present invention allows for the encapsulation of “legacy” Minet messages (i.e. MTS 22 messages) to and from the IP phones. The following message format is used:  
         [0137]    Wrapper structure for MINET messages to and from the IP Phone:  
         [0138]    ProtoType=MINET_MTS22  
         [0139]    DevNum=N where N=0, 1, 2, . . . n  
         [0140]    msgType=MINET_WRAPPER  
         [0141]    MINET_WRAPPER_MSG  
                                       msgLen:   4 bytes, unsigned long integer, length of           the following MINET message.       msg[MAX_MINET_SIZE]   array unsigned char, the MTS22 MINET           message                  
 
         [0142]    Parameters Description  
         [0143]    MAX_MINET_SIZE 160  
         [0144]    In summary, according to the present invention a messaging protocol is provided along with a collection of messages which conform to the protocol, for controlling IP Phones within an Ethernet-based PBX system. The invention has particular applicability as a message interface from Mitel&#39;s IP Phones to Mitel&#39;s IP enabled PBXs. The message interface is compatible with an H323 Voice Gateway implementation.  
         [0145]    Alternatives and variations of the invention are possible. For example, the protocol can be adapted to control voice/data switching on any IP centric node. In other words, the protocol is not constrained to phones but, rather, can be applied to any internet appliance that is a client to the IP centric PBX. Within the PBX, the protocol can be used by call control in order to control the switching fabric. All such embodiments, modifications and applications are believed to be within the sphere and scope of the invention as defined by the claims appended hereto.