[asterisk-biz] Is ISP Blocking VoIP

[Conrad Wood]

On Tue, 2006-01-31 at 21:54 -0500, Sergey Kuznetsov wrote:
> I see the only one way to do it.
> To make simple test program which will be started on both endpoints.
> Both boxes do the ntpdate right before the tests.
> then one box sends and receives the number of rtp packets with 
> increasing sequence numbers and stores the timestamps in the log
> the same is done on the second box, it sends and receives from/to the 
> first box and stores the sequence numbers and timestamps into the log.
> then they exchanges by the logs, and third perl script compares the 
> result and shows lost packets and latency for each packet in text or 
> graphics.

Actually you wouldn't need ntpdate, because you're only interested in
the difference of time when packets arrive, not the exact time.
It hence would be sufficient to put a simple
milliseconds-since-start-of-program into each packet. The receiving end
can derive the time it takes to travel from the amount of milliseconds
past since the programs started and and the declared milliseconds in the
packet. (Neglecting of course the RTT of the inital handshake, which
would need to be compensated for)
And a program like that would be tremendously useful to test QoS if it
can simulate "other load" on different ports as well.