[Hidden-tech] Vonage

[Matthew Crocker]

> I'd agree on all that, also:
>
> I think a good way to test is use it as a long distance, or a fax   
> line ;)
> Vonage's audio signal can be adjusted from low to high, and I found  
> that faxes wouldn't go through on the lower audio quality settings  
> (that was fun), so I increased my audio quality and all set ever  
> since. Can't always keep your local number even though they say so  
> (though I found out this is not unique to vonage, I checked a lot  
> of vendors, I couldn't keep mine). I did not think support was so  
> great when I used them but I hardly ever have to. As Paul says  
> network (internet or local) congestion creates audio probs  
> sometimes. It's somewhat frequent in my experience, though not a  
> major prob. On the whole it's a great deal (been using about a yr  
> on 2 lines).
>


Fax over IP or t.38 Faxing works great but Fax over VoIP does not  
work.  I would not recommend you use VoIP for your fax machine you  
will get spotty fax reception at best.

Vonage doesn't own the VoIP gateways they use.  The buy service from  
XO & Level 3 amongst others.  In order for local number portability  
to work they would need a gateway in this LATA and have a rate center  
and Local Routing Number (LRN) established for the gateways.   I'm  
not sure if XO and/or Level3 have gateways in LATA 126 (413 area code).

VoIP quality if affected more by jitter than by bandwidth  
limitations.  g.729a is only 8kbps, technically it will run over a  
dialup modem connection.   The big issue is echo cancellation.  Once  
the phone call is established the echo cancelers train up based on  
the packet latency.  If the latency is jumping all over the place  
(jitter) the echo cancelers won't be able to train and maintain sync  
and you will get severe echo.  The cure for jitter problems is QoS  
and small MTU settings over the serial link.   Ideally you would want  
to have your ISP provide QoS for you on your DSL line.   You may pay  
a bit more for this feature as QoS beats the heck out of edge  
routers.  Providing QoS queues for 4k PPPoE sessions is not an easy  
task.

-Matt

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Matthew S. Crocker
Vice President
Crocker Communications, Inc.
Internet Division
PO BOX 710
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