MGCP requested event vs. detect event

Jack, A requested event would be sent in an RQNT message, and might be for something like "offhook" or "onhook". Once the call agent has sent this to the gateway, then when it detects such an event, it will send it via a NTFY message.

If I recall correctly, I think quarantine works like this: If multiple events occur on an interface, they must be sent one at a time, with only one event outstanding in the transmit queue. Let's say the person presses a series of digits, and the call agent asked for one digit at a time (not GW digit collection).

Since MGCP sends over UDP, it can't just send them all up to the call agent because some messages could be lost, and would require retransmission. The GW can only send one at a time, in FIFO order. It sends the event, waits for an ack, then sends the next event. Otherwise, some UDP messages would get through, and others might not. Then the CA has no idea what the real digit order was supposed to have been, even though with retransmission it got all of them.

The first digit will be sent to the CA in an NTFY, and the GW waits for an ACK. Subsequent events (while an ACK is outstanding) will go into the quarantine buffer, and dequeued and sent as events are acknowledged. Same thing goes for something like offhook/onhook sequences. These have to be naintained and processed in order, or the MGC doesn't know what the current hookstate is.

Hope this is helpful.