Home page logo
/

nanog logo nanog mailing list archives

Re: VoIP QOS best practices
From: Charles Sprickman <spork () inch com>
Date: Tue, 11 Feb 2003 04:14:59 -0500 (EST)


On Mon, 10 Feb 2003, Aditya wrote:

FWIW, I purchased a Cisco ATA-186 and then a 7960 on eBay (after
trying out MS Messenger and finding it lacking) and they just work. I
also have used the same units to get a PSTN phone number routed over
IP using www.iconnecthere.com -- and you can make it work behind NAT
too (but I can assure you it's easier without NAT).

Vonage (vonage.com) let's you get your feet wet at $25/month.  Limited
outbound, but unlimited inbound and you can pick from many area codes.
They supply the ATA, and you have 30 days to play.

IConnectHere.com is the consumer arm of Delta3.  They are OK, but they
offer no help if you get stuck.  Vonage is truly plug-n-play.  Works fine
behind NAT, doesn't require any ports to be opened to function behind a
nat or firewall.  Just make sure 5060/udp and 69/udp can go out and you're
off and running.

As others have stated, it's more fun to talk about VoIP after you've used
it.  I've found the voice quality equals or exceeds my POTS line.  There
is some echo at times when the call starts, then the magic
echo-cancellation stuff seems to learn and things get better.  The delay
is fine, but can be a bit off-putting during a multi-person conference
call between excited tech and marketing folks.  But if you regularly use a
cell phone, you may not even notice this, as I find the delay on my cell
to be worse.

What I'm guessing Bill is getting at is the common VoIP implementations
out there are running UDP.  Since it's in "spray and pray" mode, you'll be
worried more about it stepping on your well-behaved TCP traffic than
vice-versa.  I'm running a codec that tops out around 80Kb/s on an ADSL
line and I've yet to find a way to affect my voice traffic.  In 6 months
of using the service I've yet to have a dropped call, and I regularly make
80 minute+ calls.

All in all I think there's less voodoo involved than most people imagine.
It just works.

Now I need to figure out how to break into my ATA so I can use it for FWD
as well (the ATA ships with an md5 key and the config it fetches via
tftp is encrypted)...  Anyone?

C

I'm willing to play tech support via email if anyone has questions
about getting started.

Adi




  By Date           By Thread  

Current thread:
[ Nmap | Sec Tools | Mailing Lists | Site News | About/Contact | Advertising | Privacy ]
AlienVault