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 newsletter!

Or

Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.
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

Father’s Day Gift Guide

Brand Post

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Luke Hill

MSI GT75 TITAN

I need power and lots of it. As a Front End Web developer anything less just won’t cut it which is why the MSI GT75 is an outstanding laptop for me. It’s a sleek and futuristic looking, high quality, beast that has a touch of sci-fi flare about it.

Emily Tyson

MSI GE63 Raider

If you’re looking to invest in your next work horse laptop for work or home use, you can’t go wrong with the MSI GE63.

Laura Johnston

MSI GS65 Stealth Thin

If you can afford the price tag, it is well worth the money. It out performs any other laptop I have tried for gaming, and the transportable design and incredible display also make it ideal for work.

Andrew Teoh

Brother MFC-L9570CDW Multifunction Printer

Touch screen visibility and operation was great and easy to navigate. Each menu and sub-menu was in an understandable order and category

Louise Coady

Brother MFC-L9570CDW Multifunction Printer

The printer was convenient, produced clear and vibrant images and was very easy to use

Edwina Hargreaves

WD My Cloud Home

I would recommend this device for families and small businesses who want one safe place to store all their important digital content and a way to easily share it with friends, family, business partners, or customers.

Featured Content

Product Launch Showcase

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?