MGCP protocol Learning (4)

MGCP normal call Process

Event 1: MGC sends the rqnt command to the gateway to monitor the terminal.
Gateway validation command. Use the same transaction as the rqnt command during confirmation Code . The Gateway monitors this event until the user is disconnected.
Event 2: After the user disconnects the host, the gateway sends the ntfy command to MGC, which contains the message about the host extraction event at the monitored endpoint.
MGC should confirm the information sent by the gateway and record the departure time.
Event 3: MGC sends the rqnt command to the gateway, asking it to collect the dialing number according to the dialing scheme, monitor the user's hanging events, and send the dial-up sound.
The gateway confirms the command and sends a dial tone to the user at the same time.
Event 4: the gateway receives numbers based on the dialing scheme of event 3. After receiving all the numbers, the gateway sends the ntfy command to notify MGC. This command carries the number of observedevents received.
MGC sends an ACK confirmation command.
Event 5: MGC sends a crcx command to the gateway to instruct it to create a connection. This command includes the callid, localconnectionoptions, and connectionmode parameters. It indicates the packaging cycle, compression Algorithm (G.711, g.729, etc.), connection bandwidth, and echo offset. Set the connection mode to the receiving mode. At the same time, MGC requests the gateway to stop receiving dialing and monitor another host event.
After the Gateway creates a connection, it sends an ACK response to MGC, which contains some connection parameters, such as IP address, port number, bearer parameter, and connection ID.
Event 6: MGC analyzes the number received by event 4 to specify the call route and establish a connection with the specified called Gateway. MGC specifies the route to the called gateway through analysis.
MGC sends the crcx command to the called Gateway. The parameters carried by this command include the connection parameters sent back by the gateway to MGC in event 5, and the same session as the meeting sent to MGC by the gateway. But there are two differences. First, the endpoint name indicates the endpoint of the called gateway, and its value is usually different from that of the call gateway. Second, set the mode parameter to the receiving/sending mode. Because the connection between the two endpoints belongs to the same call, the call ID remains the same in the command. In addition, parameters such as signalrequests and requesteevents are carried to instruct the gateway to send a ringing sound to the called party and detect the delisting signal.
The called Gateway sends an ACK response. This command includes the meeting description of the called Gateway, such as the IP address, port number, and RTP structure. In addition, the gateway sends the vibrating bell to the called device. Next, it monitors the called State until the called state is detached.
Event 7: MGC sends a qrnt command to the gateway to detect and monitor the events of the host extraction and send back the Bell tone.
The gateway sends an ACK to confirm the command and sends the Bell tone back to the caller.
Event 8: When the called Gateway detects the called detach, it sends the ntfy command to MGC to notify MGC of the events observed at the specified endpoint.
MGC responds with Ack.
Event 9: MGC sends the mdcx command to the caller to modify the connection. This command carries some connection parameters of the called Gateway, that is, the parameters carried in the ACK of the called Gateway response. Then, the connection mode is changed to the receiving/sending mode. At the same time, it instructs the gateway to stop sending the bell sound back.
Gateway gateway uses ack to respond to MGC. At the same time, it will modify the connection and stop sending back the Bell tone.
Event 10: closely following event 8. MGC sends rqnt to the called Gateway, indicating that it detects the host event of the specified endpoint.
The called gateway uses ack to respond to MGC.
Then, the caller connects to the called party and enters the call status. At the same time, the gateways of both Parties monitor the host events of the specified endpoint respectively.
Event 11: When the called Gateway detects a host event, it sends ntfy to MGC to notify the host event of the specified endpoint.
MGC uses the ACK signal to respond to the gateway.
Event 12: MGC sends the dlcx command to the gateway and instructs it to disconnect. This command includes parameters such as the endpoint name, call ID, and connection ID. It also includes the signalevents parameter to indicate that the gateway sends a busy voice.
The gateway uses an ACK signal to respond to MGC. Carry performance data fields to MGC's response for statistical analysis. At the same time, the gateway sends a busy voice to the user to interrupt the connection.
Event 13: MGC sends the dlcx command to the called gateway to instruct it to interrupt the connection. This command includes the endpoint name, call ID, connection ID, and other parameters.
The called Gateway sends an ACK to MGC, and the response carries the performance data field to interrupt the connection.
Event 14: MGC sends the rqnt command to the called Gateway, which instructs it to monitor the signals of all endpoints.
The called gateway uses ack to respond to MGC and resumes the detection of the specified endpoint.
Event 15: when the call gateway detects that the host is on the hook, send the ntfy command to MGC.
MGC uses ack to respond to the gateway.
Event 16: MGC sends the rqnt command to the call gateway, indicating that it stops sending busy messages to the specified endpoint and monitors the delisting signals of all the endpoints.
The gateway uses ack to respond to MGC and resume the detection of the specified endpoint.