Voice Over IP in UK

Author

openvox

news1001

2007-12-15, 7:11 pm

anyone using the openvoxanalogue pci cards.

any comments ?
--
news1001

cybuerke

2007-12-16, 7:11 am

"TheFug" <nosp@mplea.ze> wrote in message
news:476505d4$0$7187$ba620dc5@text.nova.planet.nl...
> news1001 schreef:
>
> What is a Openvoxanalog pci card ?
>
> --
> The Fug.

Plug in line connectors for Asterisk boxes. A la Digium cards.

TheFug

2007-12-16, 7:11 am

cybuerke schreef:
> "TheFug" <nosp@mplea.ze> wrote in message
> news:476505d4$0$7187$ba620dc5@text.nova.planet.nl...
>
> Plug in line connectors for Asterisk boxes. A la Digium cards.
>
>
Okay, i also googled this one, should i've done in the 1st place, i
guess, noticed, you can have special Asterisk installation version for
these cards, so you don't have to re-invent the wheel ;)
dont see a huge price advantage of these\cards.... so why should i
prefer this brand above the Digium ones, just because it says Open ?
Asterisks software is free to use also..and Digium support is a great
one,. and more populair i guess, or tell me what i am missing...?

--
The Fug.

Gordon Henderson

2007-12-16, 1:11 pm

In article <476515fa$0$19307$ba620dc5@text.nova.planet.nl>,
TheFug <nosp@mplea.ze> wrote:
>cybuerke schreef:
>Okay, i also googled this one, should i've done in the 1st place, i
>guess, noticed, you can have special Asterisk installation version for
>these cards, so you don't have to re-invent the wheel ;)
>dont see a huge price advantage of these\cards.... so why should i
>prefer this brand above the Digium ones, just because it says Open ?
>Asterisks software is free to use also..and Digium support is a great
>one,. and more populair i guess, or tell me what i am missing...?

I've just had a quick look myself - not that I like any sort of analogue
cards if I can help it, however ... They are cheaper than Digium cards,
but oddly enough look remarkably similar and it wouldn't surprise me if
they were a chinese clone, taking the same modules as digium TDM400P
cards do ...

As for digium support - yes, it's there, and these guys support the
development of asterisk, so it might be a nice way to indirectly support
them by buying digium...

However I've had no-end of problems getting digium analogue cards to
cancel echo on some analogue lines and support, while helpful (they read
this forum by the way), didn't help me to keep a customer. They also
have weird ideas about licensing their HPEC software which I couldn't use
due to various restrictions at the site I was at (no Internet connection
for a start) I was also told that I'd need to preiodically re-tune my
TDM400P cards - maybe weekly because that's the way it is. Riiight.

What I would say is that unless you've got perfect BT lines, you'll need
some sort of echo cancellation and if you can afford it, go for a
hardware solution like Sangoma, if it's in your budget.

Gordon

TheFug

2007-12-17, 1:11 pm

Gordon Henderson schreef:
> In article <476515fa$0$19307$ba620dc5@text.nova.planet.nl>,
> TheFug <nosp@mplea.ze> wrote:
>
> I've just had a quick look myself - not that I like any sort of analogue
> cards if I can help it, however ... They are cheaper than Digium cards,
> but oddly enough look remarkably similar and it wouldn't surprise me if
> they were a chinese clone, taking the same modules as digium TDM400P
> cards do ...
>
> As for digium support - yes, it's there, and these guys support the
> development of asterisk, so it might be a nice way to indirectly support
> them by buying digium...
>
I meant the Asterisk online guides, that are available on different
sites, and the different instant disc distro's

> However I've had no-end of problems getting digium analogue cards to
> cancel echo on some analogue lines and support, while helpful (they read
> this forum by the way), didn't help me to keep a customer. They also
> have weird ideas about licensing their HPEC software which I couldn't use
> due to various restrictions at the site I was at (no Internet connection
> for a start) I was also told that I'd need to preiodically re-tune my
> TDM400P cards - maybe weekly because that's the way it is. Riiight.
>
> What I would say is that unless you've got perfect BT lines, you'll need
> some sort of echo cancellation and if you can afford it, go for a
> hardware solution like Sangoma, if it's in your budget.
>
> Gordon

Are you saying, all these problems don't exsist on the OpenVox cards ?
I was thinking buying the Digium card, with with one red and one green
module, to setup a Asterisk server, use normal phones, and my existing
landline, so..with the Digium, i need a hardware echo canceling solution
? i live in the Netherlands, using KPN for landline (cheapest landline
sub.because i need the wire..)

--
The Fug.

Gordon Henderson

2007-12-17, 7:11 pm

In article <4766b6d3$0$19307$ba620dc5@text.nova.planet.nl>,
TheFug <nosp@mplea.ze> wrote:
>Gordon Henderson schreef:
>I meant the Asterisk online guides, that are available on different
>sites, and the different instant disc distro's
>
>
>Are you saying, all these problems don't exsist on the OpenVox cards ?

No.

Echo problems will exist on ALL analogue cards. (And some ISDN cards
too) How bad the echo is, depends on how "bad" the BT (or telewest,
etc.) line is. I was convinced one problem I had was caused by some BT
numpty using one wire from adjacent pairs from a street cab. to the
premises, but couldn't do anything about it. Plug in a £1.99 analogue
phone and it worked brilliantly. Plug in a TDM400P card and I got echo
echo echo. I tried 2 cards and a selection of modules. I tried all the
echo cancellation tuning I could get my hands on, even bought their High
Preformance echo canceller, and it still wouldn't get rid of it.

>I was thinking buying the Digium card, with with one red and one green
>module, to setup a Asterisk server, use normal phones, and my existing
>landline, so..with the Digium, i need a hardware echo canceling solution
>? i live in the Netherlands, using KPN for landline (cheapest landline
>sub.because i need the wire..)

If you only want to do a quick test, you might want to try an X100P card
if you can get it.. They sell on eBay for about a tenner.... That won't
let you hook up your existing analogue phones, but maybe a cheap ATA
would be the answer to that...

Eg.:

http://cgi.ebay.nl/ATCOM-AX-100P-Fo...
ViewItem

Or eBay item No. 130183547495 if that URL doesn't work for you.

Gordon

TheFug

2007-12-19, 1:11 pm

Gordon Henderson schreef:

>
> If you only want to do a quick test, you might want to try an X100P card
> if you can get it.. They sell on eBay for about a tenner.... That won't
> let you hook up your existing analogue phones, but maybe a cheap ATA
> would be the answer to that...
>

I already have a SPA3102, i just want to place an old pc, with Asterisk,
and a firewall somewhere in a utility "closet", and connect the network
through a gigabit switch with it...

> Gordon

--
The Fug.

TheFug

2007-12-19, 7:11 pm

Gordon Henderson schreef:
> Echo problems will exist on ALL analogue cards. (And some ISDN cards
> too) How bad the echo is, depends on how "bad" the BT (or telewest,
> etc.) line is. I was convinced one problem I had was caused by some BT
> numpty using one wire from adjacent pairs from a street cab. to the
> premises, but couldn't do anything about it. Plug in a £1.99 analogue
> phone and it worked brilliantly. Plug in a TDM400P card and I got echo
> echo echo. I tried 2 cards and a selection of modules. I tried all the
>
> Gordon

And this isn't internal feedback ? because somehow input and output are
fed into each other ?

--
The Fug.

Gordon Henderson

2007-12-19, 7:11 pm

In article <47696aee$0$25492$ba620dc5@text.nova.planet.nl>,
TheFug <nosp@mplea.ze> wrote:
>Gordon Henderson schreef:
>
>
>I already have a SPA3102, i just want to place an old pc, with Asterisk,
>and a firewall somewhere in a utility "closet", and connect the network
>through a gigabit switch with it...

An X100P is a PCI card for Asterisk to let it connect to a single phone
line. It'a a cheap way to get started than spend the money on a TDM400P
card (or clone)

Gordon

Gordon Henderson

2007-12-19, 7:11 pm

In article <47696d1b$0$19307$ba620dc5@text.nova.planet.nl>,
TheFug <nosp@mplea.ze> wrote:
>Gordon Henderson schreef:
>
>And this isn't internal feedback ? because somehow input and output are
>fed into each other ?

I don't think it was an issue with the kit. After that customer didn't
want it anymore, I recycled it for another customer and it's still
working fine today. (Well, as fine as it's possible to get - there is
still echo, but it's managable)

Gordon

TheFug

2007-12-27, 7:11 pm

Gordon Henderson schreef:
> In article <47696d1b$0$19307$ba620dc5@text.nova.planet.nl>,
> TheFug <nosp@mplea.ze> wrote:
>
> I don't think it was an issue with the kit. After that customer didn't
> want it anymore, I recycled it for another customer and it's still
> working fine today. (Well, as fine as it's possible to get - there is
> still echo, but it's managable)
>
> Gordon

But by echo you mean a delay of sound, once ?
And there's also a factor if the correct codecs are used if there's a
conversion needed, this might cause also a delay...

--

The Fug.

alexd

2007-12-28, 7:11 am

On Fri, 28 Dec 2007 01:10:59 +0100, TheFug wrote:

> Gordon Henderson schreef:
[vbcol=seagreen]
[vbcol=seagreen]
[vbcol=seagreen]
> But by echo you mean a delay of sound, once ?

I'm going to put words in Gordon's mouth here, and say "no", that's not
what he means. Echo on analogue lines can be caused by impedance mismatch
between the kit and the line, for example. This article goes into it a
bit more:

http://www.voip-info.org/wiki/view/...ho+analog+lines

Echo cancellation is expensive to fix in terms of CPU time, so it's best
prevented at source rather than cured after the fact.

> And there's also a factor if the correct codecs are used if there's a
> conversion needed, this might cause also a delay...

Possibly, but I reckon that if you're running Asterisk on a machine
that's underpowered enough for codec translations to cause significant
delay, then you're going to be having a host of other problems anyway.

--
<http://ale.cx/> (AIM:troffasky) (UnSoEsNpEaTm@ale.cx)
09:24:15 up 15:21, 2 users, load average: 0.24, 0.14, 0.10
2x Broadband/IT/Telecoms support positions in Newcastle city centre.
For more info call 0191 229 8870 and ask for Steve. No agencies.

Gordon Henderson

2007-12-28, 7:11 am

In article <4774c2ae$0$507$bed64819@news.gradwell.net>,
alexd <troffasky@hotmail.com> wrote:
>On Fri, 28 Dec 2007 01:10:59 +0100, TheFug wrote:
>
>
>
>
>
>I'm going to put words in Gordon's mouth here, and say "no", that's not
>what he means. Echo on analogue lines can be caused by impedance mismatch
>between the kit and the line, for example. This article goes into it a
>bit more:
>
>http://www.voip-info.org/wiki/view/...ho+analog+lines
>
>Echo cancellation is expensive to fix in terms of CPU time, so it's best
>prevented at source rather than cured after the fact.

That's basically it... And you can google until you're blue in the face
for other echo issues too (as I've done in the past) I think it's just
luck... My home BT line works OK using Digiums (licensed) high
performance echo canceller, but I couldn't even get that to make an
improvement on a customers line. My current strategy is to get customers
migrated over to IP provision as soon as possible, if they have analogue
equipment. (Or stick to ISDN installs, which while still having an echo
issue, is much more managable)

It boils down to 2 things: One is the quality of the far-end, and it's
ability to not inject what it hears back into what it sends back, so a
laptop using built-in microphone and speakers is about the worst case,
speaker phones slightly better (although the good ones do their own echo
signal processing and cancellation before it hits the wires), and the
decision taken many many years ago to only use 2 wires to carry both
sent and recieved voice data, rather than 4 wires. To investigate the
latter, google for things like 'hybrid' and impedance matching (along
with echo) Good luck!

>
>Possibly, but I reckon that if you're running Asterisk on a machine
>that's underpowered enough for codec translations to cause significant
>delay, then you're going to be having a host of other problems anyway.

I use a 1GHz CPUs. (occasionally 1.3GHz units for 60+ extensions) They
can quite hapilly manage 10 simultaneous transcodes of g729 to g711,
and feed this via an IAX trunk over a good business quality ADSL line,
so handling "native" g711 over analogue channels is practically no load
at all. (Although I've not done any proper performance measurements with
Digiums licensed high-performance echo canceller, but casual observations
have shown that 2 simultaneous analogue calls don't introduce any
significant load)

Hope everyone's having a jolly festive time!

Gordon

alexd

2007-12-28, 1:11 pm

On Fri, 28 Dec 2007 10:38:58 +0000, Gordon Henderson wrote:

> (Or stick to ISDN installs, which while still having an echo
> issue, is much more managable)

What causes echo on ISDN? Presumably it's not the line, as a distorted
digital signal would lead to no calls at all.

--
<http://ale.cx/> (AIM:troffasky) (UnSoEsNpEaTm@ale.cx)
15:06:57 up 5:01, 3 users, load average: 1.33, 1.21, 1.13
2x Broadband/IT/Telecoms support positions in Newcastle city centre.
For more info call 0191 229 8870 and ask for Steve. No agencies.

Dave Higton

2007-12-28, 7:11 pm

In message <47751189$0$514$bed64819@news.gradwell.net>
alexd <troffasky@hotmail.com> wrote:

> On Fri, 28 Dec 2007 10:38:58 +0000, Gordon Henderson wrote:
>
>
> What causes echo on ISDN? Presumably it's not the line, as a distorted
> digital signal would lead to no calls at all.

Yes, I wondered that. It's impossible for ISDN itself to cause an
echo. There has to be something else at the far end, e.g. a
speakerphone, AFAICS.

Dave

Gordon Henderson

2007-12-29, 7:11 am

In article <47751189$0$514$bed64819@news.gradwell.net>,
alexd <troffasky@hotmail.com> wrote:
>On Fri, 28 Dec 2007 10:38:58 +0000, Gordon Henderson wrote:
>
>
>What causes echo on ISDN? Presumably it's not the line, as a distorted
>digital signal would lead to no calls at all.

Just because it's ISDN doesn't mean there won't be echo )-: At some
point it'll have to be converted to analogue and if it then goes down
a 2-wire interface, or goes into rubbish hardware there will be echo
generated by the far-end, and there are some fancy (& expensive!)
BRI/PRI cards with hardware echo cancellers on-board... (Fortuantely,
I've not had to resort to using one in the UK yet!)

A lot is to do with time too - we don't notice echo if we hear the thing
we said in under 30mS (IIRC - don't quote me on this!), so using the
"normal" TDM/PSTN type network in the UK more or less guarantees this -
even if the far-end reflects it back, it ought to come back quick enough
for us to not be able to detect it... But going further afield, "ye cany
change the laws o' physics"[1] and the speed of light (or electricity
;-) starts to become noticable, so talking London to NY via cable,
will introduce a few 10's of mS each way, so if there's any feedback
at all at the far-end, and there are no echo cancellers on the line,
you will hear it, and it will be annoying!

Now convert a signal to VoIP and pump it down an ADSL line with a
ping time to the server of 20mS each way and things start to become
"interesting" too... Even without ADSL, there are still delays over IP -
if you have a local asterisk box, trying talking into a phone connected
to the Echo application - even going from phone via LAN to a local server
and back again will introduce enough of a delay for you to notice it.

Even in the non-IP world you can observe delay and echo - For amusement,
try calling from a mobile to a landline in the same room and speaking
to the person who answers it, making sure they can hear you through the
air as well as over the wires...

Gordon

[1] As a Scotsman, I'm fully licensed and entitiled to say that

Dave Higton

2007-12-29, 7:11 pm

In message <fl4tk2$1fgl$1@energise.enta.net>
Gordon Henderson <gordon+usenet@drogon.net> wrote:

> In article <47751189$0$514$bed64819@news.gradwell.net>,
> alexd <troffasky@hotmail.com> wrote:
>
> Just because it's ISDN doesn't mean there won't be echo )-: At some
> point it'll have to be converted to analogue and if it then goes down
> a 2-wire interface, or goes into rubbish hardware there will be echo
> generated by the far-end, and there are some fancy (& expensive!)
> BRI/PRI cards with hardware echo cancellers on-board... (Fortuantely,
> I've not had to resort to using one in the UK yet!)

My point is that the echo doesn't (and can't) come from the ISDN
bit; it can only come from somewhere else, some non-ISDN part of
the path.

The acoustic path from earpiece to microphone of even a cheap
handset is tiny. I tried it years ago, expecting it to be a
significant problem, but found it was truly negligible - on the
border of undetectable. So a true ISDN terminal, or ISDN with
a proprietary digital telephone system on the end, won't echo
to any perceptible extent.

[snip the rest, which I agree with]

Dave