[Asterisk-biz] Asterisk Business Termination -- VOIPJET

[alex at pilosoft.com]

On Mon, 22 Nov 2004, Kevin P. Fleming wrote:

> Businesses who use VOIP over a T-1 circuit have _less_ points of failure
> than if they used TDM phone service over that same T-1, because they
> have no complicated equipment in their office to worry about.
I forgot to bring up another important point: QoS and jitter guarantees if
you are doing VoIP and Internet over same circuit. It is not trivial to do
and compensate for correctly. Just to give VoIP traffic more priority than
IP, you have to have a router that understands that and can classify
traffic into classes. Nevertheless, even doing that, you still will have
to wrestle with jitter issues. Example: Assuming you have 1500 byte packet
being sent over T1 and 1ms later, you get a VoIP frame. Now, that packet
is going to take its sweet time (8ms) - thus causing jitter on your VoIP
connection. You may think its nothing - but your fax will disagree. So now 
you need a proper t.38 support on both ends, etc etc. 

Again, things are not as simple as they look (plug in the phone and 
your computer and go)

-alex