Service Level for VoIP - QoS

[guest]

Dear All,

My company is now using VoIP service via broadband. We already have a SLA with our vendor. But the problem now is the SLA only applicable to data uptime, but not VoIP. We need to have something to measure the VoIP service quality, but we were informed that the VoIP can only be measured using measuring tools like latency measurement, but can't apply service level on top of that, because if there are many people sending emails at one time, the VoIP will be interrupted (because data is given higher priority than voice), so the service level of VoIP is unable to be guaranteed. We have also been told that quality of VoIP service can only be guaranteed if we are using lease line. But then since we are not using lease line, can we still apply some benchmark to measure the service level of VoIP? Is the information given i.e.:service level is only applicable to lease line usage is true?

Hope someone can provide some advices or opinions..


Thank you.
Stephanie

[Tony]

Hi Stephanie,

There are definitely some potential QOS problems with using broadband for your company. How many employees do you have, what is your brpadband connection type/speed, what is your voice gateway?

There also some network monitoring tools out there that will monitor VoIP, however a lot of them are more geared towards larger offices. For example:

http://www.netiq.com/products/vd/default.asp

Regards

Tony

[guest]

Dear Tony,

Thanks for you reply.. My company consist of 470 staffs and with 30 over branches. We are using SDSL Line with 1.5Mbps and ADSL Line with 1Mbps. We are using VPN server as well. We already have monitoring tool from our vendor, but the problem is we need to apply QoS or service level on top of the VoIP service, not only just monitoring. Because it has no point if we can just monitor it but unable to assure the quality of the service.

Based on the info given above, is there any opinion or suggestion?

Rgds,
Steph

[Tony]

Hi Steph,

Ok, I understand your problem now (I think). You are using having QOS problems between sites using VoIP over DSL. Unfortunately you have been informed correctly. The only way to control and priortize the voice traffic between sites is to have a leased line (eg MPLS). Using the interenet for this type of solution has the downside that when you are in a corporate environment you are going to have these bandwidth issues with data traffic hogging the line.

How many T1's do you curently have that connect to the PSTN? You could reduce the number of these and replace with a leased line on which you can run converged traffic. Although the leased line cost will still be higher than T1, this would help a bit. You can then run QOS over the leased line.

Also what call-agent are you using for you using for your VoIP and who is the vendor?

Hope this is making sense.

Tony