Recommended Voice Links

[B657]

Hi,

We have installed a few IP Offices in different geographical locations that are linked into a SCN via broadband.

These have not really been successfull as the call quality between sites is just not good enough.

I understand that the quality of the voice is only as good as the adsl that connects them together, but are there any ground rules that need to be met to achieve quality voice of the broadband?

Is it just a case of throwing more bandwidth at it?

Is it a case of keeping contention to a minimum?

Are there any "voice" adsl products that are better than your normal internet connections?

Has anyone else had any experience of these problems, and is there a recommended solution here?

Thanks

 

[amriddle01]

If you are using a standard Internet connection at the mo I am not surprised you have quality issues, the only way to guarentee a level of quality is a leased line or similiar and they are not cheap! This is something you should have looked at before Installing really!!

ACS - IP Office Implement

 

[ronromano]

Simply put, yes throw more bandwidth at it.

http://www.nu-tel.com

 

[gknight1]

bandwidth might not be the issue, what about QoS???


do you have any QoS programmed in your routers and switches?

 

[ronromano]

Who needs QoS if you have enough bandwidth?

http://www.nu-tel.com

 

[gknight1]

man... i am having a tough time telling if ron is actually being serious.lol

 

[ronromano]

I am being serious. QoS is important on your weakest link. I this case it's his crappy dsl. Get more bandidth on your weak link, tighten up the compression and go home.

http://www.nu-tel.com

 

[gknight1]

it all depends on how much data is going across the link. If you are transfering a 2 gig file and you are going to make a phone call, you WILL notice problems.

 

[ronromano]

Exactly, although you example is extreme. The point is clear, QoS has it's place. Please don't try to tell me you set it up on every customer or walk away. This person should have started with more acceptable circuits in the first place.

http://www.nu-tel.com

 

[gknight1]

i am not saying i do. i was just telling him. he said he has a broadband connection, what speed is your broadband connection (up and down). how many phones does he have? he never told us any of this, so to simply say more bandwidth... i think is an incomplete answer.

 

[tlpeter]

Always tell the customer that QOS is needed at all times
If they decide not to do it you can not be blamed when they have problems


ACA - Implement IP Office
ACS - Implement IP Office
ACA - Voice Services Management
______________
Women and cats can do as they please and men and dogs should relax and get used to the idea!

 

[B657]

Ladies, ladies, please.

Here is the situation. The historical sites are history, we managed to get out without our faces being too red, the SCN was more of a "like to have" and we had said upfront that it may not work because of the integrity of the adsl (it was 2mb downstream, 256k upstream). Now if the a this is contended by 20/1 then simple maths tells you you dont have the upstream bandwidth to make a decent quality call.

However I now have a requirement that MUST work and if the answer is leaased line then so be it, but the customer will never go for that, so I need to understand what will work, and work well.

There will be no more than 4 calls going over the SCN. I propose that we have a dsl dedicated to voice, and a seperate one for data. The routers will provide an always up VPN and I will prioritise voice (although i would question whether this actually works when it goes out onto the internet).

Ronromano is correct. It was crappy adsl that was the problem previously. But this is a clean sheet of paper, so has anyone got a SCN over adsl, sdsl or anything similar that actually works, and what are the "best practices" here?

Thanks chaps,

Ben.

 

[amriddle01]

The problem is not just bandwidth it's many things. There is absolutley no priority to voice over the Net regardless how you set up your Routers! Also packet loss, delay, out of sequence packets are all out of your control,setting up a VPN just gives you a secure channel and in fact reduces your useable bandwidth it doesn't give you a set bandwidth to play with. It's ok for say Softphone and Skype but not for an SCN link, SDSL is also expensive and does not solve the other problems you get but will no doubt be slightly better. If you could get a good quality voice SCN over the Net everyone would do it...but they don't.

ACS - IP Office Implement

 

[B657]

Thanks everyone. So it seems the answer is dont use SCN if you dont have a leased line.

Crap.

 

[jamie77]

For G729 CODEC you need approx 30Kbps bandwitch per call

For G711 CODEC you need approx 80Kbps bandwidth per call

And leave a bit of space for the SCN messages to go over.

These figures are approximate. Look at the VOIP bandwidth calculator on the knowledgebase.

http://marketingtools.avaya.com/knowledgebase/

I would speak to the telco and find out how much these kind of links would cost. There are namy ways to skin a cat these days and the answers are always changing.

Jamie Green

ACA:Implement - IP Office
ACS:Implement - IP Office

http://www.alliedcom.co.uk

Football is not a matter of life and death-It is far more important!!!!

 

[amriddle01]

Well it's not really crap, many business's that use SCN have leased lines anyway for their corporate network etc and so it's great for them. If you want it for free you pay the price of poor quality and unreliability. As I said before if it worked great over the Net everyone would do it and the Telco's would lose out on lots of money, so you will never win.

ACS - IP Office Implement