INTEROP - Massive VOIP tests reveal strengths, weaknesses

The good news is that VOIP equipment among multiple vendors is finally pretty interoperable; the bad news is that there are still lots of potholes that can ruin VOIP implementation.

That's a broad view of results from Interop Labs tests of VOIP gear run on the show's test network and presented at the Lab's Interop exhibit.

Volunteers set up five model enterprise networks fitted with VOIP equipment, network firewalls, application firewalls, Wi-Fi access points and VPNs and ran VOIP calls through them using a variety of VOIP phones -- softphones, hard phones, Wi-Fi handsets and PDAs. The tests involved equipment from two dozen vendors.

The calls ran over a combination of the public phone network and the Internet using a service provider that supports SIP signaling, and then testers tried to disrupt the calls and measure the results.

Some of the results:

-- Network address translation (NAT), the masking of private IP addresses from public view, can break VOIP by making it impossible to set up SIP-based calls over the Internet to devices with private IP addresses. The best option the Labs found was to get rid of NAT if possible. If not, get a SIP proxy server that can ignore the public addresses on VOIP packets and find the actual addresses within.

An alternative is to install a server outside the NAT device -- usually a firewall -- that keeps track of where packets come from and shepherds them through the NAT.

-- Use QoS on Wi-Fi networks. While the Labs didn't quantify the difference, testers say the improvement in quality jumped dramatically to their ears when QoS was turned on. "It was noticeable even on non-busy networks," says Jed Daniels, one of the volunteer testers, who said the biggest improvement was it cut delay.

-- VPNs don't disrupt VOIP. This came as a surprise to testers, who expected that encapsulating real-time UDP voice packets inside TCP packets would cause delay, but that wasn't the case. With IPSec and SSL VPNs there was no significant degradation, Daniels says, although the quality over SSL VPNs was better.

Join the PC World newsletter!

Error: Please check your email address.

Our Back to Business guide highlights the best products for you to boost your productivity at home, on the road, at the office, or in the classroom.

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Tim Greene

Network World (US online)
Show Comments

Essentials

Microsoft L5V-00027 Sculpt Ergonomic Keyboard Desktop

Learn more >

Lexar® JumpDrive® S57 USB 3.0 flash drive

Learn more >

Mobile

Lexar® JumpDrive® S45 USB 3.0 flash drive 

Learn more >

Exec

Lexar® Professional 1800x microSDHC™/microSDXC™ UHS-II cards 

Learn more >

Audio-Technica ATH-ANC70 Noise Cancelling Headphones

Learn more >

Lexar® JumpDrive® C20c USB Type-C flash drive 

Learn more >

HD Pan/Tilt Wi-Fi Camera with Night Vision NC450

Learn more >

Budget

Back To Business Guide

Click for more ›

Most Popular Reviews

Latest News Articles

Resources

PCW Evaluation Team

Michael Hargreaves

Windows 10 for Business / Dell XPS

I’d happily recommend this touchscreen laptop and Windows 10 as a great way to get serious work done at a desk or on the road.

Aysha Strobbe

Windows 10 / HP Spectre

Ultimately, I think the Windows 10 environment is excellent for me as it caters for so many different uses. The inclusion of the Xbox app is also great for when you need some downtime too!

Mark Escubio

Windows 10 / Lenovo Yoga

For me, the Xbox Play Anywhere is a great new feature as it allows you to play your current Xbox games with higher resolutions and better graphics without forking out extra cash for another copy. Although available titles are still scarce, but I’m sure it will grow in time.

Kathy Cassidy

STYLISTIC Q702

First impression on unpacking the Q702 test unit was the solid feel and clean, minimalist styling.

Anthony Grifoni

STYLISTIC Q572

For work use, Microsoft Word and Excel programs pre-installed on the device are adequate for preparing short documents.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?