[Asterisk-Users] Help - is voip good for in-house calls?

[Wiley E. Siler]

Hello Francis,

My office build is the same as yours.  15 or so extensions, low traffic
100MB network, and a desire to have a phone system that uses VoIP.  I
have my system working as a PBX just like you would.  I use two TDM400s
for my 8 POTS lines and Polycom IP 500 phones at the desktop.  I also
tested with the Grandstream phones you suggested.  SO, we have the same
system requirements so here are the answers as I have found them for my
implementation....

Voice quality on the SIP based phones has a lot to do with the codec you
use.  The lowest compression codec is uLaw and that is what I use since
we have tons of bandwidth to spare.  Also, my HP switch has COS (class
of service which is like QOS) so I can prioritize the packets coming
from my phones over the standard network traffic.  Even without this
switching feature turned on, performance was great.  The phones
themselves play another role in the quality.  Grandstreams are pretty
good and I have only used mine for testing so I will not disparage them.
However, the old saying stands.  You get what you pay for.  Raising your
phone budget from $85 to more like $150-250 will get you a phone with
more features and greater expandability in my IHO.  However, you can
still do great things with the cheaper Grandstream phones and still have
a system that works very well. IT is all up to what you can spend and
what you need.  Google the archive by putting "site:lists.digium.com" in
front of your search string (no quotes though).  You should see some
good info on phones.  

Latency is gonna be there on any network.  However, on my network (which
is just like yours) the latency is very very low.  We are talking
20-40ms tops and it is completely unnoticeable when using the phone.
The only problem I have had at all has been with occasional echo.  It
does not happen often and it usually takes about 5 seconds for the * box
to train up and remove it.  Most of this seems to originate in the fact
that I am using POTS lines.  The solution that uses a T1 PRI has better
features and I think it has less echo potential.  However, that would
not work for me since my T1 provider wanted to make me pay 6 grand to
switch to a PRI from my standard data T1 with POTS.  Just some food for
thought...

I have been a VoIP user for about 1 month after spending another
researching what when where how...  So, we know I am not an expert...
but as a fellow user and new VoIP initiate, I can tell you that Asterisk
is a phenomenal product for SMB level offices like yours and mine.  When
I compared it to a PBX system of comparable power, expandability, and
feature set, Asterisk won easily since the only real cost I have had was
for my phones.  I have my system in place for around 3000 dollars and it
is competitive with all the 10K dollar solutions the vendors threw at me
plus it has an undeniable advantage in upgrade path.  All upgrades to
the system are free and the sky is the limit to what you can build using
the framework that all the * gurus have built into this system.  Not to
mention the fact that if anything ever goes wrong with the server, I can
have a new one in place in under and hour.  Try that with a PBX when
some proprietary part goes belly up.  You could wait days potentially.
My $.02.  Hope this helps.

Cheers,
Wiley




-----Original Message-----
From: Francis Augusto Medeiros [mailto:francismedeiros at gmail.com] 
Sent: Saturday, August 14, 2004 1:08 PM
To: asterisk-users at lists.digium.com
Subject: [Asterisk-Users] Help - is voip good for in-house calls?

Hi there everyone!

I work at an office where we plant to have about 12-15 phone
extensions. Costs of PBX are cheaper, but they are not expandable and,
as the office is brand new, I want to use all modern stuff.

My question is: if I buy 12-15 Grandstream Budgetone 101 phones, and
install and asterisk server, as well as a Digium TDM400 for POTS
access, will I have the same voice quality and standards as a
PBX-only, with "traditional" phones? Or should I go all the way to
Digium's TDM? Or should I forget the whole thing and get a traditional
PBX? ;)

My concerns are most latencies. Our network will be a switch with lots
of ports, all 100mb/s, with VERY low traffic.

I've read lots about voip, and I'm quite impressed with it, but most
case studies show voip being used to interconnect offices. My case is
different - I want to replace a traditional PBX to handle in-house
phone calls, either from room-to-room in the same building and
room-to-POTS.

Any comment, help, tip or link would be greatly appreciated!

Yours truly,

Francis
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