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

[Francis Augusto Medeiros]

Hi there Wiley!

On Sat, 14 Aug 2004 14:43:05 -0700, Wiley E. Siler <wsiler at e2020inc.com> wrote:
> 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....

Thanks for your e-mail!!! Your setup and your envoironment are really
encouraging, since they are very similar to what I have in mind
(except for the quantity of POTS lines - we won't use that many).

> 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.

Well, I'm not really looking for a lot of phone features, just the
basics (transfers, call retrieval, etc.). And voice quality is not
what I am most worried about, but the delays on the conversation.
However, on your mail, you say that latency is, in most cases,
unnoticeable, and those are great news to me, as I feel more
comfortable to suggest our office to buy ip-phones and use them,
knowing they will serve us well.

> 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'll most likely use a BRI. Do you think this will help to avoid echo?
 
> 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.

That's also what I hope it will happen here! If we want to expand, we
don't want to end up with a closed-system that won't handle more
extensions or phone lines. And since things are converging, and things
like FWD, Vonage and others are helping ppl to communicate, the use of
a voip based system would certainly help us more to communicate with
our clients and with ourselves.

Yours,

Francis