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uk.telecom.voip (UK VOIP) (uk.telecom.voip) Discussion of topics relevant to packet based voice technologies including Voice over IP (VoIP), Fax over IP (FoIP), Voice over Frame Relay (VoFR), Voice over Broadband (VoB) and Voice on the Net (VoN) as well as service providers, hardware and software for use with these technologies. Advertising is not allowed.

newbie questions - Asterisk & VOIP



 
 
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  #1  
Old June 1st 05, 04:09 PM posted to uk.telecom.voip
Geoff Winkless
external usenet poster
 
Posts: 87
Default newbie questions - Asterisk & VOIP

Hi

Firstly, some background...

I have a certain amount of experience in traditional telecoms (I used to
administer an Index PBX in my last job) and TCP/IP networking, plus 10
years commercial experience in Linux and IT in general.

My wife has her own business which now has four people working in one
office. They currently have two external voice lines with DECT handsets
(one for each line on each desk, so 8 phones in all, bleagh), which was
ok when they first started out (it was just two of them in partnership)
but now they have more people it's becoming unworkable - they need more
lines and having more DECT phones won't cut it.

I looked into an asterisk solution a while back but the cost of getting
the hardware was prohibitive for a startup.

However now they're looking at buying more physical lines it seems to me
that VOIP might be a better solution: to get 5 analogue lines (4 voice,
1 fax) is going to cost a pretty packet and will still require some
hardware to interface to a PBX.

So the questions.

In your experience will an NTL cable internet connection (2Mb, I think)
be sufficient to run 5 VOIP lines, given concurrent normal office use
(ie email, basic surfing etc) or would a dedicated second IP connection
be required?

How easy is it to interface asterisk to VOIP supplied lines from the
various suppliers (skype, sipgate etc)?

Is it worth the extra to use VOIP/Wifi phones or would you get adaptors
and use DECT? Will the DECT solution restrict usability (things like
missing callerid, exchange features etc)? Given that adaptors are 50
quid or so and wifi phones about 200, that's a fairly large price
difference...

Is it possible to link a voip phone to asterisk over the internet - so
if I take a wifi-VOIP phone home and turn it on there (where I also have
a wifi network) is it possible to link to the office asterisk install
and transparently work from home? I guess I could set up a tunnel using
my server at home but is there an out-of-the-box solution to do this?

Lots of questions, I know, sorry

Thanks for any advice

Geoff
  #2  
Old June 1st 05, 06:29 PM posted to uk.telecom.voip
The Cable Guy
external usenet poster
 
Posts: 55
Default newbie questions - Asterisk & VOIP

Geoff Winkless wrote:
|| Hi
||
snip
||
|| In your experience will an NTL cable internet connection (2Mb, I
|| think) be sufficient to run 5 VOIP lines, given concurrent normal
|| office use (ie email, basic surfing etc) or would a dedicated second
|| IP connection be required?
||

You will have to be mindfull of the upload speed available & that a high
quality codec will use 80k per call (80?)

|| How easy is it to interface asterisk to VOIP supplied lines from the
|| various suppliers (skype, sipgate etc)?
||

Skype doesn't have an Asterisk client yet, though someone is working on one,
somewhere.
Sipgate's a piece of cake, 1899 worked fine for me. I'm struggling with
18866, though many others aren't

|| Is it worth the extra to use VOIP/Wifi phones or would you get
|| adaptors and use DECT? Will the DECT solution restrict usability
|| (things like missing callerid, exchange features etc)? Given that
|| adaptors are 50 quid or so and wifi phones about 200, that's a
|| fairly large price difference...
||

Wouldn't bother with WiFi phone - Buy an adapter & plug in your Dect
phone(s).

Caller ID will still work.

Sipura make some excellent ATAs.

|| Is it possible to link a voip phone to asterisk over the internet -

Apparently so. I have not successfully managed to set this up.
||
|| Lots of questions, I know, sorry

That's what the group's for.

An excellent resource is http://voxilla.com they have some very helpful
forum moderators, who also know what they're talking about.

There's a forum for Adapters and another for Asterisk (plus others)


  #3  
Old June 1st 05, 06:33 PM posted to uk.telecom.voip
Ian
external usenet poster
 
Posts: 289
Default newbie questions - Asterisk & VOIP


So the questions.

In your experience will an NTL cable internet connection (2Mb, I think)
be sufficient to run 5 VOIP lines, given concurrent normal office use
(ie email, basic surfing etc) or would a dedicated second IP connection
be required?


Depends on the upstream speed. also depends on the call usage each call will
use approx 80kbs for G711 and 20kbs for G729, Its a case realy of suck it
and see and if you get prolems get a second line in.


How easy is it to interface asterisk to VOIP supplied lines from the
various suppliers (skype, sipgate etc)?


Well Skype is impossible at the moment, Sipgate is as it stands not suitable
for business use. Reasons include reliablity, no support for IAX and DTMF
issues
Look to the business suppliers if you want business lines

Is it worth the extra to use VOIP/Wifi phones or would you get adaptors
and use DECT? Will the DECT solution restrict usability (things like
missing callerid, exchange features etc)? Given that adaptors are 50
quid or so and wifi phones about 200, that's a fairly large price
difference...


Dect sets will have all the features you need CLI etc
Depends on how many dect sets you want if its more than a couple get a
TDM400 which has up to 4 fxs ports.

Is it possible to link a voip phone to asterisk over the internet - so
if I take a wifi-VOIP phone home and turn it on there (where I also have
a wifi network) is it possible to link to the office asterisk install
and transparently work from home? I guess I could set up a tunnel using
my server at home but is there an out-of-the-box solution to do this?

Yes, But you get issues with NAT traversal.

for more info have a look at www.voip-info.org

Ian


  #4  
Old June 4th 05, 07:55 PM posted to uk.telecom.voip
BigLarry
external usenet poster
 
Posts: 19
Default newbie questions - Asterisk & VOIP

In your experience will an NTL cable internet connection (2Mb, I
|| think) be sufficient to run 5 VOIP lines, given concurrent normal
|| office use (ie email, basic surfing etc) or would a dedicated second

|| IP connection be required

In my experience (with a 3MB NTL line) it isnt even reliable enough for
1 line, at least for a business situation.

The upload just isn't enough and without doubt you will at some stage
get situations where people just cannot hear you or at best say "its
breaking up I cant hear you".

I have learnt this from experience.

Take into consideration that someone might also be sending a large
email attachment and this WILL seriously affect your phone quality.

I'm told that moving to a 20:1 dedicated adsl contended line will allow
up to 10 people without issues to hold concurrent calls - perhaps
someone can confirm that.

Hope this helps.

  #5  
Old June 5th 05, 07:47 AM posted to uk.telecom.voip
Phil Thompson
external usenet poster
 
Posts: 2,720
Default newbie questions - Asterisk & VOIP

On 4 Jun 2005 11:55:59 -0700, "BigLarry"
wrote:

I'm told that moving to a 20:1 dedicated adsl contended line will allow
up to 10 people without issues to hold concurrent calls - perhaps
someone can confirm that.


if you use the higher quality Codecs that use 10 kbytes/s per call
then three of them would max out the upstream of a BT 256k upstream
ADSL line.

I don't know if the trunking facility of Asterisk reduces overheads
enough to help in this regard.

Phil
--
spamcop.net address commissioned 18/06/04
Come on down !
  #6  
Old June 5th 05, 03:00 PM posted to uk.telecom.voip
Tony Hoyle
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Posts: 24
Default newbie questions - Asterisk & VOIP

Phil Thompson wrote:
I don't know if the trunking facility of Asterisk reduces overheads
enough to help in this regard.


Not to the extent of supporting 10 simultaneous calls.

If the line is shared it needs QoS setup as well, otherwise other
activity on the line will increase your jitter too much. This of
course requires a router that supports it.

TBH for a business get SDSL or Leased Line. ADSL is for home users and
low usage.. not for something as critical as VOIP. I use it but the
max I'd ever use is two calls and that's rarely.

Tony

  #7  
Old June 5th 05, 03:08 PM posted to uk.telecom.voip
Tony Hoyle
external usenet poster
 
Posts: 24
Default newbie questions - Asterisk & VOIP

Geoff Winkless wrote:

However now they're looking at buying more physical lines it seems to me
that VOIP might be a better solution: to get 5 analogue lines (4 voice,
1 fax) is going to cost a pretty packet and will still require some
hardware to interface to a PBX.

Just read that bit.

Get an ISDN PRI and something like an TE110P, which will scale to 32
channels. You can still use cheap asterisk Hardware and have the same
flexibility.

Tony

  #8  
Old June 6th 05, 09:49 AM posted to uk.telecom.voip
Geoff Winkless
external usenet poster
 
Posts: 87
Default newbie questions - Asterisk & VOIP

Phil Thompson wrote:
On 4 Jun 2005 11:55:59 -0700, "BigLarry"
wrote:


I'm told that moving to a 20:1 dedicated adsl contended line will allow
up to 10 people without issues to hold concurrent calls - perhaps
someone can confirm that.


if you use the higher quality Codecs that use 10 kbytes/s per call
then three of them would max out the upstream of a BT 256k upstream
ADSL line.


10kB? Surely full uncompressed G711 is 64Kbps, or 8kB.

uh huh... http://www.voip-info.org/wiki-Bandwidth+consumption suggests
that 64kbps stream translates to a bandwidth usage of around 87kbps,
which is ~11kB, I suppose. However, that's full stream uncompressed,
you'd expect to get better than that using compression.

I don't know if the trunking facility of Asterisk reduces overheads
enough to help in this regard.


Given that I wouldn't be using it (unless the VOIP provider supports
this - do any of them?) it wouldn't help in this particular instance.

G
  #9  
Old June 6th 05, 09:59 AM posted to uk.telecom.voip
Geoff Winkless
external usenet poster
 
Posts: 87
Default newbie questions - Asterisk & VOIP

BigLarry wrote:
In your experience will an NTL cable internet connection (2Mb, I
|| think) be sufficient to run 5 VOIP lines, given concurrent normal
|| office use (ie email, basic surfing etc) or would a dedicated second
|| IP connection be required

In my experience (with a 3MB NTL line) it isnt even reliable enough for
1 line, at least for a business situation.


Thanks, that pretty much scuppers that.

Geoff
  #10  
Old June 6th 05, 01:35 PM posted to uk.telecom.voip
Phil Thompson
external usenet poster
 
Posts: 2,720
Default newbie questions - Asterisk & VOIP

On Mon, 06 Jun 2005 09:49:36 +0100, Geoff Winkless
] wrote:

10kB? Surely full uncompressed G711 is 64Kbps, or 8kB.


that's the Vo bit, now you need to add the IP. Lots of little packets,
lots of overheads. Not very efficient really. My 10 kbytes/s was read
off Netmeter while I made a call, BTBBV reports similar, I didn't just
make it up to depress you :-)

uh huh... http://www.voip-info.org/wiki-Bandwidth+consumption suggests
that 64kbps stream translates to a bandwidth usage of around 87kbps,
which is ~11kB, I suppose. However, that's full stream uncompressed,
you'd expect to get better than that using compression.


what does the compression ? Why not use GSM codec instead.

I don't know if the trunking facility of Asterisk reduces overheads
enough to help in this regard.

Given that I wouldn't be using it (unless the VOIP provider supports
this - do any of them?) it wouldn't help in this particular instance.


http://www.voip-info.org/wiki-Asterisk+bandwidth+iax2

yes there are VoIP providers supporting Asterisk connections for
trunking rather than just individual clients registering direct to
their server.
http://www.voiptalk.org/products/VoI...rvices/iaxtalk (arbitrary
example)

Phil
--
spamcop.net address commissioned 18/06/04
Come on down !
 




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