First question would be what is the customers quality expectation. If it
is to use for business and not always sound like VOIP G729 won't cut it.
The other issue with G729 that I have found is DTMF. We do a lot of DTMF
transmission during the call and have had nothing but headaches. By
going to uLaw and dtmfmode=auto that issue went away. Seems issue is
that some where along the line, when the calls were going from 729 to
ulaw for termination they wanted inband ( which doesn't work in 729 as
far as I can tell) and the outofband either wasn't being passed or
utilized to insert into the inband stream.
Just to give you heads up it seems to be in the termination end and from
our experience happens in Alberta and the east coast. US and Ontario
never really had a problem.
Only other possibility which I haven't played with yet is 726, but looks
promising. From what I've read quality is there, and half the bandwidth
of ulaw. Just don't see a ton of support in devices. But since your
controlling the 2 end points and not using SIP hardware ( I've not seen
any phones w 726 support ) it could give the quality, a compromise on
bandwidth and transcoding overhead is a lot less then 729.
My main server is a dual xeon 2.4 GHz, 1GB ram, w SATA Raid 0+1 (
4x120GB), with 5 concurrent calls in as 729 transcoding to ulaw and
recording the calls as wavs was taking about 7% CPU utilization
(fluctuates between 5.5-7.9). I think fluctuation peaks are due to IO
bursts. At idle system utilizes 0.2% CPU. We're anticipating that this
server should be able to handle 60-70 concurrent calls with recording
enabled (will be hitting limits CPU or Disk) or , but will probably in
reality only have 30-40. We're just waiting on some other software to
finish development before ramping it up.
Hope some pieces of my ramblings are of use.
Mike
Ian Service wrote:
What do you mean by horrible? CPU-wise, quality-wise? Just curious,
because I got my licenses all set up a while back and found the call
quality wasn't great and blamed my endpoints, but could it have been
asterisk's fault? Should g729 sound almost as good as ulaw?
- Ian
On 3/17/06, *Shidan* <[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>> wrote:
Dude I thaught the diagram was reversed. Do you really have to go
out thru your G729 provider, if you tell me where your gateway is,
im sure you can find someone tier-1 voip who
terminates close to your gateway striaght ulaw. G729 is absolutely
horrible with asterisk.
----
Shidan
On 3/17/06, * Leif Madsen* <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
On 3/16/06, Leif Madsen <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
> I need to take 4x T1's into an Asterisk box (92B + 4D) and
transcode
> them from G.711 (ulaw) to G.729, terminating via SIP. I've
been at VON
> this week in SJ, talking to the Digium guys, and opinions seem to
> hover around a box with 2x Intel Xeon CPUs running at 3.0GHz or
> higher.
Just as some added information, which doesn't really affect the
original question, but will help you visualize the topology I'm
dealing with. The box will be sitting at a customers side and
acting
as a "transcoding gateway". The customer will be the one
filling the
physical T1 ports with their equipment, where the streams will be
transcoded by Asterisk to G.729, then sent via SIP to my gateway
servers where I will terminate his traffic to the PSTN.
Customer -- [4x T1 ( G.711)] --> Asterisk -- [SIP (G.729)] -->
Internet
--> GW --> PSTN
Hope that helps clear up any confusion as to how this is being
implemented.
This also allows me to bring up another part of the scenario
-- have I
calculated correctly that with all protocol overhead (SIP,
RTP, UDP,
IP + codec media) that I'm looking at around 2.12 Mbps of
databit rate
for all 92 simultaneous G.729 calls?
--
Leif Madsen.
http://www.leifmadsen.com
http://www.oreilly.com/catalog/asterisk
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